I see, so you want the run-once to preserve the program repeat settings. There is currently no easy way to get around it — run-once works differently from a normal program, and as its name suggests, run-once is just an one-off program that does not repeat. For a repeat schedule to work, it has to be set as a normal program. At the moment you will have to keep using your current way: change the program start time.
I would like to see a fuction where if a temperature is reached by a sensor then a specified zone will run for a period on a repeat cycle
e.g. temperature exceeds 28°C, run for 20 seconds every 3 minute