Ah, I see you're still on the "come up with something" topic
I'm not vey happy with the use of "think up" in this context, but I can't tell you why. Just doesn't sound right. So I could be wrong.
She "invents" would be understood, but I'm still not very pleased with it.
She "comes up with" interesting activities sounds perfect.
EDIT: I feel like Goldilocks, tasting a bit of papa bear's and mama bear's porridge, before I get to the one that's just fine
Thanks Nichec, for sticking up for me
Actually, I performed a search and "to think up" is, apparently, quite common (I wonder what planet we're living on... Earth to Nichec and Trisia...!).
If you don't trust me, see it yourself
Still, they mention that it's used especially when you invent/create/make up excuses (lies )