I realize that epilepsy and narcolepsy are not the same thing but they are similar. Epilepsy is something I have researched very thoroughly because I have it.
Some of the best info I have found is coming out of Johns Hopkins. (A reputable medical institution. Not something that can be dismissed as some fringe internet pseudo-sci junk.) Goggle them + ketosis and you will find all kinds of stuff about their work on treating neurological disorders with diet.
I have been able to cut my dose of those nasty meds by 25% while maintaing total control of my seizures.
I wish you and your daughter well.