Lazy is relative. Lazy compared to a hamster? Yes. That's o.k. Lazy compared to a dog or cat? That's o.k. too. Lazy compared to you? Again. That's o.k. Your snake is going to be lazy compared to any mammal, and it should be. Conserving energy is key to their survival.
Now, lazy compared to itself, how it used to be? That's a tougher question. Most likely your bp's behavior is perfectly fine. BPs are sedentary even compared to other snakes, but a description of your set up would help us determine if there is something there that's contributing to its inactivity. Pics are helpful too. Here's a link that will show you how to post them: https://ball-pythons.net/forums/show...-Post-Pictures.