Hi trangle1611,
First off, a 640/Q47 is a solid score (it's just a bit shy of 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/As it stands, you're actually closer to a 700+ than you probably realize - and you could potentially improve a great deal with another 1.5 months of study. With a V31, you likely lost serious points in at least 2 of the 3 major Verbal categories (SC, RC and CR), so you will likely need to focus on more than just CR during the next phase of your studies. You might want to consider purchasing the Enhanced Score Report. While the ESR doesn't provide a lot of information, there are usually a few data points that we can use to define what went wrong (and what you should work on). If you purchase the ESR, then I'll be happy to analyze it for you.
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