On the server page, under Manage → Reinstall, you can run your server’s installation again. This helps if game files are damaged, an update went wrong or a startup variable requires a reinstall (e.g. a different beta branch or Workshop mods).
Important: The server is stopped in the process, and depending on the game, files, worlds and settings are overwritten or deleted. Create a backup under Backups first.
Reinstalling usually takes a few minutes. You can follow the progress in the Console; afterwards, start the server as usual.