There hasn't been any breaking changes.
You can save/load both your projects and your icon sets (see the menu on top right of a set). Also, every icon pack you download from the IcoMoon app comes with a "selection.json" file which you can import back to the app to retrieve your selection along with your other settings.
If you are a premium member, we keep periodic backups of your data. So even if you accidentally remove your projects, we can retrieve them. Reach out via the
contact form for more info.