Hello Herbert,
Although the changes don't apply until you restart the station, the configuration file is re-built every time you hit the "save" button in the station's configuration area. So, when somebody changed the admin password, both the database and the configuration file are updated at the same time.
You can set your application to re-read the configuration file if the current password fails, and that's all you need to do.
But to answer your question directly, you can't decrypt the password stored in the database.
HTH