It would seem that your ACT-Science score is an aberration. However, you would need to improve AT LEAST to a 31 on a retake in science to improve your composite by one point ASSUMING your other scores remain the same. Indeed, a 34 is MUCH better than a 33 with some of the most selective schools.
By contrast, the SAT might give you a better opportunity to improve because of superscoring. Do your favorite intended schools require that you disclose ALL you SATs regardless of superscoring?