What should a controller say if an aircraft is maintaining the same route beyond a holding fix?

The appropriate phrase to use when instructing an aircraft to maintain the same route beyond a holding fix is "Cleared to proceed with the last routing." This phrase effectively communicates that the pilot is authorized to continue on the previously cleared flight path.

Using the term "cleared" indicates an official authorization from air traffic control, which ensures that the pilot understands they can resume their previous routing without any changes. This is crucial for maintaining clarity in communication and ensuring operational safety. The phrase also encapsulates the critical aspect of continuing the routing, which helps to avoid any potential confusion that might arise if the aircraft is unsure whether the last routing is still valid.

In contrast, other options might not provide the same level of clarity or official authorization. They may indicate continuation but lack the decisive "cleared" that signifies official permission from air traffic control.