I think you should ask these questions to yourself first: How are the other areas of your application? If they are good, then your current score is fine. But, if they are missing something, then having an impressive score can compensate for the insufficiencies in other areas.
HOWEVER: Having said that, from your question I can guess how your character is like. If you don't retake it you will forever say to yourself "what if". So, even if it is only to remove that "what if" from the remaining of your life, it may be worth to take it again.
An interesting story from myself: When I was in high school we had teachers/advisors who told us to what colleges to apply based on their thorough analysis of our skills. In the country that I was applying things were a little different. You took a centralized test held by the ministry of education, and based on your score in that test you would be allocated to the appropriate college. The top college in that country is almost impossible to get in. You have to be in top three among 10000 test takers to get in. My advisor told me to not apply to that college because he saw my chances slim/non-existent. Of course, I didn't agree. I would rather apply and not get in than say "what if" to myself whole my life. I applied, and I got accepted. I was top 2 in the test.
So, it is up to you, but sometimes being insane pays off.