Is there anyway to prevent a root canal?!

Is there anyway to prevent a root canal?

I go to the dentist every 6 mo to have my teeth cleaned, I floss EVERY day, I brush 2x a day. My dentist refilled a tooth 2 years ago that had a deep cavity, and now it is sensitive and he says I will need a root canal. Is there any way that I can reduce the chance that I will have to have a root canal? I rinse with Listerine, and peroxide and water, but what else is there?

When you have a large filling in a tooth removed and refilled there is always a chance that bacteria entered into the canals and that is what causes the discomfort that you have experiencing. It has nothing to do with seeing your dentist, (you are doing a good job with that), or with how often you brush and floss ( good job there too), but with the fact that you had a decay before and it is not too difficult for decay to form under a filling.
What type of filling was replaced?
If it was one of the silver/mercury fillings, after time gaps form around the margins of the filling and decay burrows down under the filling... right to the nerve chamber.
Rinsing with Listerine and peroxide and water are good for the gums but do nothing to prevent decay (contrary to some advertising claims).
If the tooth is starting to bother you... don't wait to have it treated. You'll be much happier with your own tooth restored than having it extracted and a bridge or implant placed. Your own tooth will always be best if it can be restored.