The people that I know that do a fall crop still start the seeds indoors, usually under lights. Once sprouted, they can be moved into a protected area outside, but not into the full summer-time hot sun. If your plants are healthy, you could break off branches/suckers and root in moist potting mix instead of planting new seeds. I would still root the cuttings inside, though, just so that it is a little easier to control the heat and moisture.
