So you get a loli and impregnate her, then you wait until she gives birth, then you impregnate the loli that was born (wait for her to become fertile of course, but you can train her before that), then you wait until she gives birth, then you impregnate the loli that was born, then you wait until she gives birth, then you impregnate the loli that was born. and you do that until either the inbreeding kills them before a new baby can be born/at birth or until you can no longer impregnate them (luckily age hits men weaker in terms of fertility, so you can do that for a while)