Thanks for the quick reply. She hasn't been putting on any extra weight, so I don't have to worry about that. I'm going to try switching her over. She's near the end of her latest kitten food bag.
Having just made the same transition, I would advise making a gradual switch. 25% new food/75% kitten food for 3-4 days, then 50/50, then 75/25, then 100% new food.