You could try looking at the LivingMath! website for non-textbook ideas. We have heaps of recreational math books at home, mostly Martin Gardner, but also a stack of Murderous Maths, Theoni Pappas books, and a random assortment of others. DS9 also goes on Vi Hart and Numberphile binges.

There are also lots of math books like Balance Benders out there. My kids generally like doing these, and don't consider them math.

DD8 seems to be similar: good at math, but seems to think she isn't and says she hates it. I'm working on turning it around, too. This summer we are trying a combination of Khan Academy (she tolerates) and LoF (she loves), which I think of like dinner and dessert.