Hi, does the new server have a different name and ip address from the old epo server. Also, did you reinstall epo, or just rename the server from the original server.
If its a rename and new IP, then the easiest way will be to use DNS. Update your DNS server to privide the ip address of the new epo server when the agent looks for the old server. Once the agent has connected to the new server, it will pull down its full information.
If you have rebuilt the epo server, did you keep the server keys from the old server. If not, then the old agents will not be able to connect to the new server, unless the agents had been upgraded from version 3.6, or are still on version 3.6.
Otherwise you are probably looking at resinstalling the agent from the new server on all your machines.
If you want all your client should communicate with the new ePO server. do one think
1) Check the old epo Serve configuration check the communication port.
2) Server setting
Note down all the port and install fresh epo when it comes to the port screen put all port which is mention on the old epo server.
Best of luck...