Is this the salvia 'hot lips' with red and white flowers?
If so, take fresh shoots without flowers from the base of the plant, about 3 to 4 inches long, and insert into a compost which is half peat/compost and half vermiculite or grit. Water well, and cover with a plastic bag. Leave in a light warm place, but not in direct sunshine. With luck, the cuttings should root after a few weeks or a month. Check the plastic bag frequently to make sure the shoots are not rotting, and remove it as soon as the cuttings seem to have formed roots.