I use Tetrosyl 'trade spray' acrylic clear gloss lacquer, which comes in 500mL cans. You can spray acrylic over cellulose, so whether your existing lacquer is acrylic or cellulose, it ought to be safe. (If you spray cellulose over acrylic, it risks acting as a solvent and wrinkling the acrylic). It's use extensively by woodturners and gives a high gloss finish. I've also used it on 'woodies'
https://www.tetrosylexpress.com/prod...s019/TETATS019
Hope that's of interest.
Well done on your efforts by the way!