Developer tools → States. Find your sensor entity. In my case, “binary_sensor.kitchen_dishwasher_sensor”. Set its state to “off”.
I went back into the device and then disabled and re-enabled the sensor. (Takes a couple of minutes). Tested this a couple of times.
Thanks. I managed to get it back to dry (and in general behave as expected) shortly after I posted my question. I can’t remember now what I did although I think it was something different to your suggestion.
My workaround for ZHA not resetting to dry via push is to poll when it thinks it’s wet with this blueprint, in case it’s useful to anyone here.