Hi RuchaV,
With a 690/Q45, you have a fantastic GMAT score that would make almost every Business School happy, so retesting is probably NOT going to be necessary. Since you haven't defined the specifics of your situation, there are a number of factors to consider:
1) What schools are you planning to apply to?
2) When are you planning to apply?
3) What are the other details of your application (work experience, essays, etc.)?
4) How you would handle an interview?
5) Are you applying for any scholarships?
Etc.
Barring certain Finance-specific MBA programs and other "specialty" programs, if you applied and were wait-listed (or rejected), it would not be because of your GMAT score. If you're planning to apply to any competitive programs, you might consider working with an Admissions Expert who could help you to make your application as strong OVERALL as possible. To that end, you should pose any questions that you have to those same Experts (there's a Forum full of them on this site).
GMAT assassins aren't born, they're made,
Rich