The instructions for my recently completed Fairey Huntsman kit state that excess canopy glue when dry can be removed with a very sharp blade and tweezers taking care not to scratch the transparent surface. Dave Milbourn knows what he is talking about.
If using solvents then check they won't affect the perspex - some do.
Before using a very sharp blade it might be worth trying something like the edge of a credit card which won't scratch the surface.
Colin