Plant fell/ broke off from stem

She is doomed, nothing will save her and planting new seeds is your only realistic solution. By the time you cloned her, if possible and seeing she has already wilted/dehydrated , your new seeds would be 3-5 times as large by the time she rooted, and if it is an auto, cloning would be pointless due to the limited vegetative cycle before flowering begins. Also, next time, fill your pots right up, this will provide much more room for root growth. More roots = more plant growth. Hope this helps,.......... Organoman.