Fading unfortunately is permanent. There are dye kits for exterior trim, but I don't think I would recommend that for interior, and even so it is a temporary fix. I would keep it protected with a quality product. 303 and OPT protectant plus are very good. OPT opti-bond tire gel is actually great on the interior. It gives a nice gloss, if you like that, and may enhance the color a bit. Once UV and Ozone have begun the degradation process its too late. You can only control it at that point.
I don't recommend the cheap greasy OTC products like armour all, etc... They are greasy and petroleum based. They give a darker color through the silicones and oils in them giving the illusion of a black finish, but they will eventually fade and ware off. And the distillates will just dry out the rubber and plastic. So grab some 303 or OPT and keep it protected.