Miscarriage woes

The llama I have trained for years was recently purchased by my boyfriend and I. We suspected all summer that she was pregnant because the normally flirtatious and sweet girl no longer showed interest in the boys and was now a bit standoffish. Of course, we could never be sure since no one hand bred her and the males are in other fields. Recently, the farm owners called saying that a llama had miscarried a cria and it looked as though it was premature. My suspicions had been confirmed when they found the poor dead cria. Does anyone have any ideas what could have caused it? It was her first and she was probably 3 or 4 when she was bred. Also, we want to breed her again and were wondering what anyone else thought about it particularly risks and chances of her carrying a baby to term this time.