For the client side, you'll have to get a new sylink.xml to the clients, there are multiple ways to do this.
1) Use the "sylink dropper" tool
2) Script a stop SMC \ replace sylink.xml \ start SMC process.
The security sforums for endpoint protection have many articles as well as tips and tricks for this procedure.
For the server side see:
https://www-secure.symantec.com/connect/forums/need-rename-server-sepm-runs
https://www-secure.symantec.com/connect/forums/renaming-server
https://www-secure.symantec.com/connect/forums/renaming-endpoint-managment-server