I know about
unity --reset command.
But how can I simply restart Unity without resetting its profile?
which starts a new GUI connected to your terminal. however, if you run this over SSH, ehm, this is probably not the best IDE, because your local desktop 'unity' instance is then bound to this terminal on your remote-desctop...
funny things occur, when you terminate this session. Step by step your GUI will vanish and the only thing which remains under your control is the pointer of your mouse.
I found this post really helpful, which sumarises the commands mentioned in other answers.