Armor all wont really do it. Its like putting a wet finger on a chalk board to see it turn darker.
The chances are hight that after 15 years, the paint is fully oxidized. This is like rust for paint and plastics...depends what’s underneath.
The plastic, it depends.
I deal with strong sun here in Denver. Frankly, i bring my stuff in , even if shaded, to avoid the inevitable bleaching. Uv is strong even under the trees.
I use a product called classic dry wash and guard. Nfi
Its meant for concours cars.
I used it on a 60 year old raleigh bike with hand pin striping, which had dulled.
The product shined the paint, and took off the oxidized surface without harming the delicate red pin stripes and gold water decals.
Its a miracle product. It has ultra fine pumice suspended in a non mineral solution, snd as you rub, the pumice breaks down to even finer micro particles.
I use it on guitar finishes, and plastics.
It is your best bet, imho, with the above caveats. If the paint or plastic is fully baked and oxidized throughout, its unlikely to help.
Another more available oprion might be mcguires glaze car wax. Super low abrasion, but, mineral base, so some decals might be affected. Fully dry ink and paint graphics, probably not. Youll need to be prepared to clean the residue from plank crevices, etc.