Unfortunately, applying sideart (especially full size) takes a lot of work to get the surface very smooth, and it's not trivial to install it either. If the old artwork is absolutely perfect aside from fade, you might get away with installing new art over it, but few people would recommend that because it's kindof janky. On the other hand, removing the old artwork is not easy and getting that particle board super smooth is a lot of work. I mean like a few weekends of work.
There's no easy fix. Actually, the easiest fix would be to sell that one and buy a non faded one, if you're not chomping to test your sideart installation skills.