First things First. Take a proper backup of your database. If we understand you correctly you want to change the ip address and the host name of the machine on which the SEPM is currently installed. Once you have the database backup in place things would be easy. To achieve this do the following :-
1. Create a custom Management Server List, containing both the old and the new host name and IP address, and assign it to all client groups.
2. Make all clients check in and update their Management Server Lists.
3. Re-name the host in the Properties of My Computer; also make sure to make any needed changes in your DNS.
4. After re-starting the host to apply the name change, run the Server Configuration wizard. It should default to offering the new host name for the server name; make sure this change is selected and otherwise complete the wizard with the values that it had before you set out to make the change. Especially, use the same database password as for your old installation.