Pretty sure by the time "Ralph Breaks the Internet" was in development, she was busy writing and directing Frozen 2. Nevertheless, writing for an animated film is always a collaborative effort, and Disney has so many more talented writers than just Jennifer Lee.
Disney has a lot of "good" movies and even a few "great" movies, but only ones written by Jennifer Lee have managed to crack my top 10 favorites list. So, no Jennifer Lee means Wreck-It Ralph II will probably be just another good movie, which is kinda disappointing.