You can reuse it but make some fresh about every other day. Sounds like some of them are hurt pretty bad around the mouth. When they bite each other in the mouth like that, it swells up fast and then gets a bit infected, preventing it from healing.

Depending on how bad it is, at first it might look like it's getting worse, especially since it will sometimes bleed a bit. That's OK. The important thing is to get that stuff in the wounded area even if it has to bleed a bit to do it. Then any gaps around the mouth should be lightly covered with the ointment afterwards. I know it's rough on all of you but you'll see. Give it some time and you'll see it's healing. It may take some time for the gap to begin to close even after the infection is gone and the swelling has gone down. Anyway, after a few days, maybe a week, it should stop bleeding when you apply it and you'll see the red inflamed gums turn to pink. When you see that, you'll know it's working. I would keep this up for at least 10 days. 14 would be better. It's also very important to keep the container they're in VERY CLEAN. Wash it often and change the paper towel daily. Feed them small meals because of the handling and treat them an hour or two after their meal.

This medicine and this treatment is exactly how vets treat mouth injuries or infections in snakes. Just keep it up and save on the vet bill.