As David said, there is no way to get a faded sparkle to return to it's darker, original look. The tinted clear wrap idea is interesting though. Might be able to use a car window type sheet of tint. I'll have to look into that.
At any rate, I'm restoring a vintage Kent red sparkle kit currently. The kick, floor and mounted toms are pretty evenly faded with no major blotches or anything weird. The snare however, is a different story. Not sure if it's an original member of the kit or not, but it's quite a bit lighter than the other drums.
What I'm doing to all of the shells, is going over each one using Mothers California Gold Sealer & Glaze. Normally used on car finishes, it's actually very usable on sparkle drum wraps (satin flame not included) as well. It's excellent at taking out fairly deep scratches and removes the layer of gunk which builds up over the years. It contains a super fine grit for polishing as well as a wax to restore some shine. You can lay into it pretty hard without fear of going too deep into the finish. Do not however use a buffing wheel or similar, unless you try it on a test shell. I do it all by hand - Tedious and tiresome, but I haven't ruined a wrap yet.
It did a great job on the toms (kick still to be done) and helped the snare as well, though not as much due to the fade. Once each shell has been polished, I'll apply a couple of coats of Carnuba wax. This helps protect the wrap and also darkens it slightly while adding even more shine.
I've tried other basic cleaners on the shells (Fantastik, 409, etc...) but none of them gets down deep enough to remove the grunge from the pores in the wrap.
I'll snap a few pics of the kick before and after and post them.