I have the same problem with Kaya's top knot hair. All of a sudden it's like it disappeared. Her hair is thin to begin with. Now there isn't enough there to do anything with.
I don't know of a way to make hair grow faster... just good nutrition and supplements.
I can't keep the cloth ones in any of my dogs - they slide right out. I wish they would stay in, it would help a lot. The clips, well, they slide around and never stay put. Maybe I don't know how to put them in right.
Geez, if we can put people in space, we can surely figure out a good way to keep top knots in without wrecking hair!!!