Dropping a year is a very risky decision and has its own consequences. So it’s better you analyze your prospects and inclinations before forgoing an offer from any IIM be it Bodh Gaya or Sambalpur. It requires a lot of courage to risk an entire year just to target a better B School. Sometimes it’s worth it and sometimes it’s not. So I will suggest you to forgo such an offer only if

• You have a perfect plan to prepare excellently for CAT next year and you are confident you will score a higher percentile 
• You are good at the DILR section. Even if you prepare for your CAT again, you cannot improve much in the DILR section. You can improve your quantum and verbal skills but not much in the DILR section. So if that is one of your weaknesses, I don’t think leaving the offer is worth the risk.
• You are going to work somewhere and gain experience. This is very crucial as during the interview you cannot say you took a drop year merely because you wanted to prepare for CAT.

I will say that IIM Bodh Gaya is not bad of a choice mainly because it is an IIM under the mentorship of IIM Calcutta.

I am sure my answer will motivate you for the best. Trust me not joining IIM Raipur was one of the best decisions you took. That B Schools is a substandard educational institution neither good for learning nor staying and making memories. People who join IIM Raipur are the ones who have literally no other option. 

• The faculty is poorly experienced and the classroom learning is not even mediocre. 
• There is no extracurricular activity culture at all. No events are conducted to promote cultures and no festivals are celebrated 
• The hostel facilities are the worst here. During peak summers, the cooling system is switched off to cut down on expenses
• The CTC mentioned in the placement reports is inflated and highly misleading 

All these points clearly say that joining IIM Raipur would have been a grave mistake. So I suggest you try to excel in your current job and then slowly look for a better job or MBA opportunity.

Honestly speaking CAT is a very unpredictable exam and one should not risk his career by forgoing such an opportunity and relying on the CAT solely. I will suggest you avail this fantastic opportunity of getting into IIM Rohtak especially if you

• are a fresher and have an academic drop of more than a year
• have more than 3 years of experience 
• are a GEM who managed to get into an IIM

In either of these cases it’s highly recommended you just grab this fantastic opportunity and give up on sitting for CAT again.

Usually, an MBA is ideal for working professionals who already have some experience at hand. The MBA program further helps you connect certain subjects to your experience working in an organization, which is good for learning. But there are instances wherein even freshers end up landing high-paying jobs. In the end, it’s just your own willpower and determination which decides if you are ready to join a B School or not.

I know it is a tough decision because I have seen my sister in a similar dilemma last year. What she did was focus on the below 3 aspects and made a decision.

Work Experience: It’s not understandable that with a work experience of 3+ years why you are only targeting IIM Lucknow and not other top IIMs like A B or C. Also if you don't want IMTG, you should wait and give GMAT and try for ISB.

Educational Background: Your chances of getting into IIM Lucknow next year depend largely on your past academic records which cannot be changed. So you need to ensure they are enough to make you eligible for the cutoff and worth the wait.

Lastly, you should be confident of the risk you are willing to take. Choosing IMTG vs IIML is a no-brainer. So check whether you are choosing IMTG just because you are not confident of being able to get into IIM Lucknow next year or not.

Honestly, both institutes have their own legacy and are excellent in the finance sector. Yet here I am writing some major points in favor of IIM Lucknow based on my cousin's experience.

Placements: The placements at IIM Lucknow for finance have been doing exceptionally well with the highest CTC standing at INR 53.34 LPA and the average CTC at INR 32.21 LPA. A good number of front-end roles, corporate finance roles, and foreign markets desks based out of India were offered.

• Front end: JP Morgan, Citibank, Morgan Stanley, Black Rock, Kotak, Investec, Avendus, Arga Investments
• Foreign markets desk based out of India: Deutsche Bank, Bank of Americal Merryl Lynch, Citibank, Goldman Sachs
• Corporate Finance roles: HUL, Mondelez, Airtel

Faculty: The top-notch faculty offers the best classroom learning backed up by Guest lectures and Industry workshops to promote maximum exposure.

Learning: IIM Lucknow offers a wide range of electives to choose from based on your interests. Some of them include Investor Psychology, Quantitative applications in finance, Project Finance, Corporate Banking & Risk Management.

SPJIMR is also a good choice for Finance but from what I have read, many major firms that visit IIM Lucknow don't visit SPJIMR so this might limit your opportunities to a small extent.

Forgoing an admission offer from Calcutta and preparing for UPSC is a risky choice. Whether this is a good decision depends on your goals and how soon you are willing to achieve them. If you are falling short of time, then you can devote the entire 2 years to UPSC preparation. 

But if you prefer quality over quantity then my suggestion would be to pursue MBA along with it. Surely the first year will be challenging. You might face serious issues managing both the tasks at hand. But trust me the results will be amazing. Pursuing an MBA will change your perspectives regarding the issues around the world. You won’t just study for UPSC you will learn from it. Moreover, you can select management as your elective in UPSC. Management and administrative services are correlated. 

If you have less time in hand forgo the admission offer and prepare for UPSC. But if you want to crack a qualitative UPSC pursue MBA along with it.