Deleting all dchp-scopes wiht one command

Is there some command i can use to delete all dhcp scopes at once?

I have following Idea to duplicate DHCP server: I use netsh command to
backup dhcp server and I restore the backup to other DHCP server with netsh
command.
I'm planning to do that backup and restore every night. But I think that I
should first delete all scopes from secondary DHCP before restoring or does
that restore overwrite excisting data?

--
Petri Siiskonen