This is tricky and sometime GUI backup and restore may give you errors like function not supported or cannot import the DataBase.
Using this powershell method, there is no error and using verbose logging you can also see the logs at the same time.
Use below PowrShell to export the scopes from old server to new server.
Export-DhcpServer -File C:\temp\DHCPDB.xml -Leases -Force -ComputerName fra-winapp01.prg.ori.local –Verbose
then move the XML file exported at the c:\temp to new dhcp server.
Then run the below command to import the dhcp scopes to new server.
Import-DhcpServer -File C:\temp\DHCPDB.xml -BackupPath C:\temp\ -Leases -ScopeOverwrite -Force -ComputerName dhcpprg1.prg.ori.local –Verbose