I agree it isn't super immersive, but it's hard to raise the difficulty on this kind of game without making it a total grind. I think a potentially good option is to add some diminishing returns and gift progression instead. My idea: After giving her a certain amount of the same plush she gets less satisfaction from it, but the shop starts to unlock higher tier gifts like a giant plush, workout dumbbells, and other things Korra might like a lot. I think that makes her happiness seem more believable without necessarily rebalancing the pacing of the game.