For those 31 days Casey was sneaking back to the house (emphasis on sneaking). Per her phone pings, she was there primarily for short periods of time, probably raiding Cindy's fridge, looking for cash and picking up clothes. And ofcourse quite possibly on one trip, trying to bury Caylee. I just don't see her taking time out to go seek out her old journal, jot down some very deep and potentially incriminating thoughts then leave Hopespring without it. Whether fantasy or not, I don't think ICA figured she would have to live with the folks ever again.