Yes the UV LED flashlights help the charge of the glow disc last longer when compared to a standard LED flashlight. However they don't make crappy glow plastic suddenly become long lasting glow plastic, nothing can. For example that colored glow plastic from Discraft is mostly garbage (CryZtal FLX Glo) and nothing can help it stay lit.
IMO There are a lot of factors to consider when it comes to Glow disc golf. The amount of moonlight can be a factor, on a full moon night the glow discs become harder to find do to it being less dark. Glow discs are easier to spot when it is really pitch black out vs moon lit nights. The weather is also a factor as glow discs don't hold there charge as long the colder it gets, below 30-40 degrees I would rather use tape on LED lights instead of glow plastic.
Personally I keep my glow discs covered up at all times when not in play. I have a dedicated glow bag I keep zipped up and a box of back up glow discs with a covered lid to keep their exposure to light low. I assume like most things glow plastic gets weaker over time and prolonged exposure.