Hi GIRISHSVVS,
Most Test Takers who use a 'book heavy' approach get 'stuck' at a particular scoring level; that may be what's happened to you. When you say that you couldn't crack 720+, does that mean that you have scored 720 or that you haven't gotten close to 720?
Before I can offer any specific advice, I'd like to know more about your overall studies so far:
1) How long have you studied?
2) What materials have you used besides the ones you've listed?
3) How have you scored on each of your practice CATs (including the Quant and Verbal Scaled Scores)?
4) What is your goal score?
5) When are you planning to take the GMAT?
GMAT assassins aren't born, they're made,
Rich