Just one guys opinion:
I don't think you need to change your hit points. Even if one person has busted out before the rebuy period, he is still out of the game until he rebuys. Therefore, by the end of the night, he/she will have busted out at least twice. So I think, whoever knocked that person out deserves the point, whether it's the first time or the last. The person re-buying is getting another change to win the pot, so the hitman deserve the point no matter when the bust out occured.
Once again, just one guys opinion