I believe that different universities have different policies when it comes to looking at multiple GRE scores from an applicant.
And regarding your situation, taking the GRE six times is a very expensive and stressful thing to do. My cumulative score is actually lower than yours, although I am from a different field. I don't know much about the requirements for your program but if I were you, I will focus on strengthening the other parts of my application instead of having another round of the dreaded GRE.