Is Chemistry subject test score good enough?

I got a 760 on the chemistry subject test. Should I take it again and try to get an 800? Will that boost my chances of going to the top schools or not really? Is there really a difference between a 760 and 800?

A 760 is a fine score. Move on to other aspects of your application. If a college rejects you with a 760, I truly doubt they would have accepted you with an 800.