Unfortunately, from the FAQ on his web site:
4. I need a bite plate on a Ponzol mouthpiece replaced.
Bite plates on the new stainless steel and anodized mouthpieces can be replaced easily. I no longer have material to replace bite plates on the older brass mouthpieces.
If you still have the old bite plate and it is in good shape, it can be re-attached with some DAP or Loctite clear silicone - use the stuff that is safe for aquariums. That is what Peter recommended to me a couple years ago.
If you don't have the plate, I guess I would contact Mojo or EZ or one of the other re-facers around to see if they can do it.