Follow the steps below in order to change the hostname of the server running Symantec Endpoint Protection Manager with a replication partner:

Note: Before you proceed it is strongly recommended that, you should back up the database.
For best guidance see the document: 
Title: 'Best Practices for Disaster Recovery with Symantec Endpoint Protection'
Document ID: TECH102333
> Web URL: http://www.symantec.com/docs/TECH102333

1. Create a new Management Server List with the new host name of the server
2. Assign the Management Server List to the group which belong to that particular site
3. Once the changes has been replicated between the replication partners make sure that the clients have the same communication settings
4. Change the host name of the server
5. Reboot the server
6. After reboot run Management Server Configuration Wizard without breaking the replication partner
7. Select the option Reconfigure The Management Server and complete the Wizard
8. Login to Symantec Endpoint Protection Manager and Initiate replication

References
Title: 'Recommended Procedure for SEPM IP Address Change'
Document ID: 2008122212510448