What have you been doing since the last test where you scored a 630? Considering you scored 39 in verbal and 42 in quant, your score should be around 650. So 630 isnt a huge deviation. Improving 50 points in 2 weeks involves some studying and huge luck, to be frank. But there is no reason why you cant. Study well for the next 11-12 days, relax the day before the test. Give the GMAT prep twice in this duration. Be positive and go for the test. Best of luck.

Without knowing the specifics of your strength and weakness, it would be improper for anyone to give any credible advice here. You provided us with some very general statements.

--Quant--
What areas are you struggling?
Is it a timing thing?
Is it your approach to question? (You a type a or type b person?)

--Verbal--
CR - you can ignore. too hard to improve
RC - are you taking notes? that helped me. beyond that, too hard to improve
SC - scope for improvement...topic by topic however

I would basically focus on either quant or verbal if I had two weeks and wanted to make a significant improvement. Perhaps the most significant piece of advice I can give you, is to not worry about it. I know it doesn't help given that you said it was the last time you were going to take this test; i think you're putting incredible stress on yourself by making this the be all end all. Last year I sat my GMAT once, flew back to Asia to do it on the very last day of 2009 becuase I really wanted to apply for business school that year. Screwd up got 650. This year, when I did it second time, got 600. Don't know what happened. But I booked in two more tests after. The third time I sat it, I didn't take it seriously, knowing this was a practice and I had another test after this. I used huge words in the AWA i wouldn't normally use, and I started taking notes for the first time in RC for the verbal section. I got 740. Yes luck played a part, but upon reflection, the other factor that played into this was the fact that I simply didnt care if i got a low score, i just wanted above 600.