You will need to run the Migration and deployment wizard. This is generally found in the start menu under the Symantec Endpoint Protection Manager folder.
It will allow to create your package(s) for deployment and install the new clients with the new SEP. You can choose a deployment group and type of deployment for the machine. Furthermore you will be able to choose what portions of the package to deploy.
The SEP uses a file called SYLINK.XML to establish and maintain connectivity with the client. It is created with the package(s) and contains a key provided by the server for connecting to the server.