To rejoin a circuit that was broken using the Break Circuit command, go to
Ribbon: DM Electrical->Circuiting and Homeruns-> 
Join Circuit
Pulldown Menu: DM Electrical->Circuiting and Homeruns->Join Circuit
You will be prompted to select a broken loop to rejoin.
Select circuit to join:
The two pieces of the broken loop will be removed and replaced with a connected loop between the two devices.