There's some debate over this subject. From our experience, once a plant is flowered, it won't immediately flower as vigorously after returning to its vegging state. The longer it stays in veg, the more normally it will flower, until it reaches the point where it flowers as strongly as it can again. The less progress it makes during its time flowering, the sooner it will return to normal. So, just letting it preflower to show sex shouldn't set it back enough to cause a problem with next flowering.
Imo it's easier to take and flower one extra clone than to flower and reveg the mother.