After doing a quick google search, it appears you can easily migrate your DHCP server as long as you have both your current DHCP server (running Server 2008 R2) and a new Windows Server 2012 server you are going to designate as a DHCP server.
- Login to your new Server 2012 R2 machine with the DHCP role installed
- Open up a Powershell shell
- Execute the following command to export the configuration from the Server 2008 R2 DHCP Server
- Execute the following command to import the configuration into your new Server 2012 R2 DHCP Server; must be an Administrator running this PowerShell command.
- Import-DhcpServer –ComputerName win2k12r2.corp.contoso.com -Leases –File C:\users\yourusername\Desktop\dhcpexp.xml -BackupPath C:\users\yourusername\Desktop\backup\ -Verbose
Notes: Credit goes to the following technet article for the powershell commands and a more in-depth explanation: http://blogs.technet.com/b/teamdhcp/archive/2012/09/11/migrating-existing-dhcp-server-deployment-to-windows-server-2012-dhcp-failover.aspx