Ok, first of all:
Do MCAT scores predict USMLE scores? An analysis on 5 years of medical student data
I realize this is a USMLE and not a COMLEX study, however, it is still a board exam. This study shows that although there is an association between MCAT scores and board scores, it is a WEAK to MODERATE association. There are other studies I have seen with COMLEX, but there are many other variables aside from the MCAT, which is why I didn't post them here.
Secondly, you took classes 13-15 years ago and STILL scored 503?! AMAZING!!
Thirdly and lastly, yes, I understand that it has been a while since you have taken those classes. I think that retaking them and kicking sweet booty in them would definitely show that you are a rockstar. However, this is MY opinion ONLY. (other people's opinions do not have to become your reality!!!)
It's up to you to decide what to do next
Feel free to PM me if you'd like to chat more