Hi yskchaitanya,
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) What materials have you used?
2) When you took these CATs, did you take the FULL CAT (with the Essay and IR sections)?
3) Did you have to rush to finish the Verbal section (and guess on a bunch of questions)? Did you leave any questions unanswered?
4) When are you planning to take the GMAT?
5) When are you planning to apply to Business School?
To score 650, you're going to have to make some significant improvements to how you handle BOTH the Quant and Verbal sections, so you'll have to put in some serious study time. Thankfully, the GMAT is a consistent, predictable Exam, so you CAN train to score at a higher level.
GMAT assassins aren't born, they're made,
Rich