GRE Score advice: Should I retake the GRE?
This seems to be a common question, and I think the primary question you should ask yourself is: will retaking the test significantly improve my score? If the answer is no, then I would not bother. Generally speaking, if you didn't have some extenuating circumstance during or before testing, such as a serious illness, I would not expect the change to be quite so significant.    

Competitive applicants have good GREs perhaps as a consequence of the ability of the applicant, and are not necessarily competitive because of their scores itself. There are some other relevant answers regarding GRE scores. see: 1, 2, 3