Hi SunthoshiTejaswi,
First off, a 680/Q49 is a fantastic score (it's right around the 85th percentile overall), so it could be enough to get you into your first-choice School. As such, a retest might not be necessary. Depending on the Schools that you plan to apply to, you would likely find it beneficial to speak with an Admissions Expert about your overall profile. There's a Forum full of them here:
ask-admission-consultants-124/Since you appear to have had such a rough time with RC when you took the Official GMAT, I'd like to know how you studied and the 'steps' that you go through when dealing with a typical RC prompt:
1) How long have you studied?
2) What materials have you used (and did you use any specific materials for RC)?
3) How have you scored on each of your CATs (including the Quant and Verbal Scaled Scores)?
4) Can you describe the work/steps that you do when dealing with an RC prompt?
GMAT assassins aren't born, they're made,
Rich