Nail biters are on a quest for order, and scheduling regular manicure appointments will help you acheive that order. Biting only contributes to more ragged edges of nail plate and skin, which leads to even more biting, which leads to even more ragged skin/nails. If the nails/skin are properly taken care of, there will be no ragged edges at which to bite.
Book TWO manicure appointments per week for 2 weeks, then one weekly for 2 months. After that time, you shouldn't have anything left at which to bite, and your nails will be 'happier' for it