Ming from Agents of Speech explains why children with language delays won't do practice tasks at home for praise alone. Bring something they actually want, make it visible, and use it to signal when the task is done. Praise doesn't work as a reward for these kids.
Chapters
If they don't understand the task, you have to demonstrate it over and over again in the clinic. It's very easy not to need to use any sort of reward or whatever at home. Is like a home court advantage for your kids. They never had to do stuff with the parents to learn language related tasks. Therefore they take it for granted that they can just roll around and run off. If you can sit your child down to do some sort of task, remember that a reward is always very important. It doesn't matter what other therapists say on the Internet, because sometimes if you don't have something that the child wants, it's as if the kid's working on no salary. When that happens, the kids think, my house, I can run around and get toys while I listen to you. It's always very practical to have some sort of reward or parents will say, oh, my praise is the reward. Yeah, that's running on a very inefficient fuel, as I would say. Because sometimes if you only praise the kid, they get happy. But if they don't have anything tangible that they can see and get, it doesn't signal to them that is the end of a task.