Might take to a new lamb if you can find one within a day or two. Around here the dead lamb is often skinned and the skin tied onto the new lamb for a day. We prefer to put her in an adopter - once her milk has gone through the lamb and out the other end she'll usually accept it. She'll start to dry up in a day or so if she doesn't have a lamb to suckle. Might pine for her lamb, might not. More likely if she's lambed before and knows the score. It's probably easier on the ewe if she's away from other ewes and lambs for a few days, although the company of an old ewe or hoggett can help.