You could put a piece of duct tape or masking tape on the inside of the top of the shoe, where the shoe's tongue rubs. Put one piece of tape on each side of the laces, of course. Then the tongue would be rubbing against the tape rather than the inside of the shoe. And the tape wouldn't show, since it's on the inside of the shoe.
I'm not sure what kind of tape would work best for this. The tape has to be strongly adhesive, but the non-stick side has to be somewhat slippery. Use your best judgment, I guess!
Also, over time the heat of your foot may cause the tape's adhesive to become less tacky, and the tape might slide, so you may need to replace it every so often.