The title says it. I couldn’t see any option to undrop a dropped show on the mobile new interface.
UPDATE: My bad, I just checked the forum and found the answer. Turns out you either have to add it to your watchlist or mark an episode as watched. Still, I think having an “undrop” option would be way better. Also, this worked on the Trakt website, but the show still isn’t popping up in the “continue watching” section of a third-party app I use. It might just be an issue with that app, but I wanted to mention it anyway.