My daughter has no enamel on her teeth and the permanent veneers keep falling off!

Unfortunately your dentist might have cut your teeth too radically, or he might not follow the protocol for proper veneer bonding.Veneers need to be bonded properly.Since I have not seen the preparation, I can not tell you if the teeth were prepared too much? or you might be needing crowns at this stage !I do recommend your dentist to bond with 4th generation bonding agent, and use actual composite rather than resin cement, and I hope not all enamel was cut aggressively, if so now you are candidate for a crown. The preparation of veneers, and the method of bonding, and bite analysis directly impacts the longevity and the results.

The bonding technique must be done very precisely and very well isolated (no moisture)Bonding is more successful to enamel but bonding to denting has great results with today's bonding systems. A more  important factor is the bite. This is how the teeth fit together and how they touch during chewing and grinding while sleeping. We use the T Scan software to balance the bite which will increase the longevity of the bond and increase the porcelain life. 

The absence of enamel is called
Amelogeneis Imperfecta. We have treated many patients with no enamel and
have had excellent results. There are very specific adhesive agents that
should be used with this condition when placing veneers or all-ceramic
crowns. More than likely, your doctor is not using the correct adhesive
and cement to place the veneers. Ask your doctor what type of adhesive system
he/she is using. In my opinion, a "Total-etch" adhesive system
(the doctor should know what this is) should be used with a resin cement.

Veneers need enamel to bond correctly -- if the teeth were too aggressively shaven or there was not much enamel, the best solution may partial or full crown. If you are having this many problems, I would also seek treatment or advice from another local dentist. It may help you get to the center of the problem, especially if the veneers are being placed improperly.Also, remember, though veneers are beautiful and sturdy, they can have problems that your regular teeth do not. Is your daughter having trouble with any type of food in general?

Veneers are a replacement for enamel and stick best to enamel but can bond to dentine as well. If they are falling off again and again, then either they might need replacing or teeth might need crowns.

That might be the problem. Veneers bond best to enamel. If there is no enamel, the bond will be very weak. Perhaps the teeth need crowns instead of veneers.