I ran across some old worn brushes in the bottom of my toolbox and was wondering if there is any way to restore them to use again? Can you take a pair of scissors and trim them down finer? Any ideas welcomed.

You could try bathing them with some liquid soap, which softens them!
As for me, when I have an old brush, I keep it for drybrushing and applying pigments, and get a new one for painting works (I don't have an airbrush, so I always need plain brushes)!