Take cuttings during periods of rapid growth, usually spring and autumn. You might want to fertilize the plant a few weeks before this growth starts, since the more robust the cuttings, the faster they will root.

Humus in the potting soil will keep the cuttings robust. Not too much nitrogen, though, because you will want the cuttings to harden off as it cools. More nitrogen is needed for spring cuttings, with increasing warmth.

If you are in Illinois USDA zone 5, try placing an array of various sizes of shredded leaves around your bed, with a tarp covering the fort or makeshift cold frame when dormancy comes, and remove it in stages as it warms. You may have to do some pruning to make the bed tidy an compact enough. Someone in Twin Cities, Minnesota kept zone 7 plants alive in his zone 5 yard this way.

I have my Hot Lips plant in a pot so I am able to bring it in for the winter. I think I will try and take some cuttings now and again in the spring. I plan to plant the potted plant in the ground next year and will try putting leaves around it like you suggested . Thanks for your help.

This plant will kneel and layer itself - ie: it'll often have little rooted babies all around it, from stolons or prostrate branches, that are better/faster than rooting fresh cuttings (although that's plenty easy, as described above). The processes described above are the best, but I'd warrant that a few cuttings would root in a glass of water easily enough.

Also, this one has come true from seed, though you might get some interesting, wonderful surprises that way, too!