After removing the lettering the surface might be scratched and/or dull. To return it to the original smooth finish, try 3M Polishing Paper. Most good hobby shops stock it packaged in large sheets (8x11) under the ZONA brand. If you're a good shopper, you should be able to locate a package of the large sheets for what most places charge for the small sheets.
Read and follow the directions for the best results.
Complete set of 6 long lasting 3M polishing papers. Set includes 1 sheet each of grits 400, 600, 1200, 4000, 6000, & 8000. Washable and re-usable wet/dry papers. Each sheet is 5-1/2 x 8-1/2 inches. These polishing papers feel like paper towels, but they have a micron-graded abrasive bonded to the surface. They can be folded up and used like traditional sandpaper or wrapped around paint sticks or dowels to create the shape you need. They can also be washed when they become charged with sanding debris.Matt