Hi SunakshiSanjuAgg,
First off, a 650/Q50 is a strong score (it's right around the 80th 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:
https://gmatclub.com/forum/ask-admission ... tants-124/GMAC has publicly stated that the Official Score that you earn on Test Day is within +/- 30 points of actual ability, so this 650 isn't a far 'off' from your practice scores as you might think. Assuming a similar 'swing' in how your CATs function, and the fact that all of your scores are within 50 points of one another, it's possible that your score range has a "low end" of 650 and a "high end of" 700.
That all having been said, if you'd like to delve a bit deeper into this, then we'd need to know a bit more about how you took your CATs.
When you took your CATs:
1) How did you score on each of your CATs (including the Quant and Verbal Scaled Scores for each)?
2) Did you take the ENTIRE CAT each time (including the Essay and IR sections)?
3) Did you take them at home?
4) Did you take them at the same time of day as when you took your Official GMAT?
5) Did you ever do ANYTHING during your CATs that you couldn't do on Test Day (pause the CAT, skip sections, take longer breaks, etc.)?
6) Did you ever take a CAT more than once? Had you seen any of the questions BEFORE?
Thankfully, the GMAT is a consistent, predictable Exam, so if you choose to retest, then you CAN train to score at a higher level.
GMAT assassins aren't born, they're made,
Rich