OH - OK - thanks for the explanation. I had read some of the threads here but only quickly, and I had thought that the subbing process modified the surface of the plastic to accept an emulsion, in a way that would permanently affect the plastic. I did not realize it only worked once! I was talking about removing the emulsion - I thought that bleaching and fixing the existing emulsion could be a bit costly, but it is worth considering. Ferri bleach and fixer do last rather a long time.
But wouldn't adding a new emulsion make the resulting total gelatin layer(s) rather thick?