Hi shubhamgmat1312,
Before I can offer you the specific advice that you’re looking for, it would help if you could provide a bit more information on how you've been studying and your goals:
1) How long have you studied?
2) What study materials have you used so far?
3) How have you scored on EACH of your CATs/mocks (including the Quant and Verbal Scaled Scores for EACH)?
4) What is your goal score?
From what you describe, it does not sound as if you have considered any other Schools besides ISB, so you might want to do a bit of research into other Programs that might offer the type of Degree that you are interested in. In that same way, you can define other potential application deadlines, average GMAT Scores, etc. so that you can plan out this next phase of your studies (as well as the rest of your overall timeline).
GMAT assassins aren't born, they're made,
Rich