Sooooo, here's what should happen...
As you currently have a Load-Balanced Site (i.e. Multiple SEPMs connected to the same DB), the default Management Server List for the site will automatically tell the clients to assign the SEPMs with an even priority. This means that if you uninstall and delete a SEPM from the site, then all the clients will automatically connect to the other one.
The thing to be aware of is that readding the second SEPM as a replication partner will not restore this behaviour. As a separate site (with it's own DB and everything), the second SEPM will get added onto the default Management Server List with a lower priority (or higher priority weighting number, however you want to word it). The difference in priority means that all clients will use the SEPM in the old site first, and only switch to the new site if the old SEPM become unavailable.
You could always create a custom MSL to give both sites' SEPMs the same priority again, but this is not recommended.
Is this what you want? Perhaps you could provide a bit more info on your requirements as replication is not right for everyone. In fact, Symantec recommend keeping the number of SEP sites to the minimum required:
http://www.symantec.com/docs/TECH92051