Simple commands to move DHCP from one server to another.

To export:

netsh dhcp server export c:\Temp\dhcpdb all

To Import

netsh dhcp server Import c:\Temp\dhcpdb all

Open up the DHCP MMC add-in and authorize the server on the New server and Deauthorise the old server.
Then Stop and Disable the DHCP Server service on the old server.