Once you use one type of lip fillers, is that the only type you can use?

First off, Juvederm and Restalyne is the same product, Hyaluronic acid, just different manufacturers. So no problem there. Your next best option is fat transfer, as it lasts longer. Be sure to consult with a board certified plastic surgeon, good luck.

Hello
Thankyou for your question. It is absolutely fine to use different tiles of filler in the lips. As long as the filler is designed for use in the lips. Sometimes this is even done purposely to create the desired look. It’s best to discuss with your injector so they can assess you and what look you wish to achieve. 
Hope this helps and good luck.