Hi Yashkumar,
First off, a 680/Q50 is a strong score (it's right around the 85th percentile overall), so you should apply to any Business Schools that interest you. 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. Assuming a similar 'swing' in how your CATs function, your 2 Official Scores and your various CAT scores show that you essentially performed the same way each time (around 700 +/- a few points). The fact that your recent Official Score is almost identical to your score from 10 months ago implies that there are certain subtle aspects of Test Day that you have not properly trained for though. At higher-and-higher score levels, the GMAT becomes really 'sensitive' to little mistakes (especially on 'gettable' questions) - and if you truly had an upset stomach for much of the Exam, then that might have 'thrown off' your performance a bit.
1) When are you planning to apply to Business School?
2) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich