Srpay on 2 or 3 light, repeat light coats so as not to possibly damage the lettering.

I have an airbrush and for small projects like this I spray the Krylon into a cup, transfer the contents to my air brush cup and shoot. Takes all of about 10 minutes including cleanup and I don't need to mask usually because the airbrush is so accurate. I have saved a number of decals, or what's left of them, using this method.