When should I retake the GRE?

I just took the GRE. I got 450 on the verbal and 780 in Math. Unfortunately I am not natural science major, but I study social science and my focus is statistical research. I am not a native speaker. The application deadline is approaching soon, and I really do not have time to retake it so soon. But, I would like to retake it and get as high score as possible before the new GRE comes because I eventually need the GRE score for my Ph.D anyways. I rather retake it now and score high, and keep the record for 5 years. I studied barron's 4500 words, and did countless prep tests. I was scoring 550-640 on prep tests, but the real test was really hard. Any study tips for non natives?