Hi Bhamini,
A 650 is closer to a 580 than you probably realize (and you could potentially pick up all of those 'missing points' in the Quant section). With a Q37, you have a few different 'issues' though. First, you likely don't know all of the content areas really well (math rules, formulas, the 'step-by-step' math work that's required on most questions, etc.), so some extra practice in those areas is probably necessary. Second, you missed out on a lot of 'strategy-based' points, so you would likely benefit a great deal from focusing on Tactics (especially for DS questions). Third, you would have likely made a number of silly/little mistakes and you might have had a pacing problem on Test Day; both of those issues require you to work on your 'precision' (note-taking, organization, etc.).
All of that having been said, you could potentially retake in a month and hit your goal; however, 1-2 months of consistent, guided study will probably be needed.
1) How many hours can you study during a typical week?
2) When are you planning to apply to Business School?
GMAT assassins aren't born, they're made,
Rich