We turned off our demo site, since it provides you with only limited functionality.
Please note, that installing privacyIDEA from scratch is totally easy. On a naked Ubuntu, it roughly takes you 5 minutes. There is also a ready made ISO by the company NetKnights, that installs the Ubuntu LTS including privacyIDEA, so you can easily do a clean, fresh start. You can get the ISO at Github.
If you prefer a simple hosted solution for more elaborate tests, you can got to the partner D9T, who provides simple a hosting solution, where you can simply start your own system.
You can also go to NetKnights, who provide privacyIDEA Enterprise Edition and get your own privacyIDEA testing instance.