Keith, I rather think you're asking the impossible. Thirteen-year-olds vary widely in their tastes, level of reading maturity, yadda, yadda.

My only recommendation would be to widen the variety of books that she's exposed to. Give her the gamut. For instance, at thirteen, I would have thought that the Anne of Green Gables type of book would be of interest to her.

But whatever, keep encouraging her to read!