Do you mean the hoof is wearing down? If so, get the farrier out there asap, tell him the issue over the phone so he can bring all the necessary equipment, she may possibly need some sort of protective shoe.
Also, probably best to get the vet out to check why she's dragging it after a month. Was she on any painkillers or ABs for it at first? Did the vet actually come out to treat it or did you do it yourself? I'd assume it needs looking at if she's dragging her leg after a full month.
Satin Reign aka "Misty"... my life, my love, my everything.