Changed activation keys and already registered server can't see it.

Hi all,

I have just add another child channel to existing activation key. When I register new server it can see the new channel. But all systems registered before the activation key change can't see it. Is there any way to make them see it ? Re-register them ?
Or in general: how to cope with scenario when we add another channel to Satellite and want it to be seen on all/some already registered systems ?