understanding why it's low is the key. was it always like this? if so, has anything changed around the same time? if not, is she simply too distracted by things like work, parenting, etc?
What may help is introducing some sensuality/romance. Offer her a massage, give a lingering good morning kiss, go on a date. Look into ways to improve intimacy outside of the bedroom, and you may find that things improve inside the bedroom as well