You are better off waiting for the next round and having a higher, and therefore more competitive, score. R2 with a lower score isn't going to be any better than R3 with a good score.
I would not expect your score to increase dramatically in 3 days, but in a few weeks, you could do it. Check the Web sites for the schools you're applying to; many will post the last date when you can really take the GMAT and still get your app in for specific rounds.
btw, disregard your Kaplan
test score. As you've seen, Kaplan
scores can easily be 100 points below your scores on other tests.