How can I improve my chemistry score for NYS regents?

I took six regents this year as a sophomore I’m done with my requirements basically. However I got a 78 in chemistry, I want to retake it in January. However I’ve seen the strange grading rubric, how can I get a 90+? Same goes for physics this year when I take it? I have my Barron’s books and everything, I had a 100 in the class. People are saying my score may have been caused by too many regents , but I just feel like I can do better. Any advice?