Assuming the plants are on your property and near the house, get an outdoor flood light aimed at the plants, set it on a timer and make sure they are getting 18+ hours of light per day. They'll revert back to veg after a couple weeks.

Playing around with light cycles is an easy way to cause hermies. However you don't really have any other options... either this or get new clones and start over with supplemental night time lighting until the days get longer.