Good question. I know she was in the last update when I was checking for the pics for my comment post.
Maybe the save from the last episode and the one from 22. and then i'll see from which I pick up. Thanks!
The paths are prioritized that way:
Sandra (+Haley) > Adrianna (+Haley) > Lisa (+Haley) > Haley only
meaning, for instance, if you're on Sandra's path, it will automatically supersede the other ones, whatever your choices regarding these paths are. The last choice to be out of Sandra's path is episode 11, the last one to be out of Adrianna's path is on episode 22. At this point if you're out of these two paths, and did everything to be with Lisa, you will be on her path; if not you'll be on Haley only path.
Anyway, Lisa's apparitions are pretty scarce. She will be there for her sex scene in episode 21, and reappear only in the last episode ("28"), only if you're on her path.
This save is at the end of episode 22, on Lisa+Haley path, after refusing to move in with Adrianna. I also have saves at the end of episodes 23, 24, 26 and 28 (25&27 are Sandra exclusive episodes) if you prefer.