Here's the technique I use.
1. Dress the fly prior to use by submerging in a good silicone (liquid) floatant for at least 30 seconds.
2. Let dry for a minute or so before using.
3. After each fish, clean off the fish slime well, then wash the fly by holding the leader just above the fly, and swishing it back and forth in the water.
4. Dry the fly by a few short false casts, snapping the fly to remove excess water.
Usually, this lets the fly float like you just started out. Occasionally, though, you have to dry the fly with an amadou patch, and redress.
A little work, but it gives me good results.