Hi swats2020,
To start, I'm hoping that you can clarify something you wrote: the last 5 questions in the Verbal section and the last 2-3 in the Quant - did you NOT answer those questions at all (meaning that time ran out and you physically did not even read them) or did you have to rush through those questions (and blindly guess on all of them)? I ask because those two situations would have significantly different impacts on your Score, so we need to define exactly what occurred on Test Day.
A 640/Q47 is a solid Score, so it could be enough to get you into a Top-20 School. As such, a retest might not be necessary. Many Test Takers spend 3 months (or more) of consistent study time before they hit their 'peak' scores, so it's likely that you just have not put in enough time and effort to have scored higher yet. You've asked some Admissions questions though, so you would likely find it beneficial to speak with an Admissions Expert about your overall profile and plans. There's a Forum full of those Experts here:
https://gmatclub.com/forum/ask-admissio ... tants-124/If the Admissions Experts think that you 'need' a much higher Score to get into your first-choice School, then you have to decide what is MORE important: getting into that School OR getting into any School in the Top20 in the timeframe that you have defined. The process of applying to (and ultimately attending) Business School will require a big investment of time, money and energy on your part, so you really should make sure that the Programs that you apply to match your career goals/needs.
Before I can offer you the specific advice that you’re looking for regarding your studies, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) For this recent attempt, how many hours did you typically study each week?
2) On what dates did you take EACH of your CATs/mocks and how did you score on EACH (including the Quant and Verbal Scaled Scores for EACH)?
Goals:
3) What is your overall goal score?
4) Do you have a list of Schools selected yet? What are the exact application deadlines for the Schools that you plan to apply to?
You might also choose to purchase 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 on Test Day (and what you should work on to score higher). If you purchase the ESR, then I'll be happy to analyze it for you.
GMAT assassins aren't born, they're made,
Rich