Hi Vivekm26,
To start, if you are only looking for BOOKS of practice questions, then there might be a limit to how much you can improve (since working through lots of book-based materials will not properly train to you face an adaptive Exam taken on a computer. If you have already used an Official Guide, then you might find the subject-specific books (the Quant-only and Verbal-only books) to be helpful. Depending on which version of the OG you have used, you might also find a slightly older version (or a much newer version) would include a number of questions that you have NOT seen yet. Of course, there is also GMATClub - and there are LOTS of practice questions for you to work on here.
Going forward, you have to be careful about confusing "quantity" of study with "quality" of study. If you are stubborn about changing how you 'see' (and respond to) the GMAT, then you will likely continue to score at the same general level, regardless of the number of practice questions that you work through.
Before I can offer you any additional advice for your studies, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) How long have you studied? How many hours do you typically study each week?
2) What study materials have you used so far?
3) On what dates did you take EACH of your CATs/mocks and how did you score on EACH (including the Quant and Verbal Scaled Scores for EACH)?
Goals:
4) What is your overall goal score?
5) When are you planning to take the GMAT?
6) When are you planning to apply to Business School and what Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich