How much Innova do you feed her? Is she free-fed? Or is she just getting a lot? From one of the other discussions it sounds like Innova is pretty dense and therefore you only should feed a small amount. Cats can easily overeat on stuff like that so you need to give it to them in meals, not free-fed. (Gizmocat, Innova is pretty darn good stuff.)
What kind of toys does she like? Play with her with a lot of interactive toys- wand toys, mouse on a string, lazer pointers, and just throwing small toys for her to pounce on. And rotate the toys that she plays with alone. Is she getting bored with that catnip mouse? Put it in a drawer and give her a different one. Then switch them in a couple weeks. It makes old toys seem new again. While you're storing a toy you can put it in a container of catnip so it absorbs the scent. Cat trees and simple things like box hideaways and paper bags can get her moving.
Also, if she's an only cat then getting her a friend could make her more active. It gets boring during the day with no humans around, but another playful cat to wrestle with can change that. My kittens take turns chasing each other around the living room and onto furniture.
I think cats do well in apartments and small houses without ever going outside. It's just a matter of maximizing your space (cat trees, cat shelves, cardboard box toys) and encouraging her to exercise.