It looks like that people that were supporting Hillary are becoming more concerned, but not supporting anyone else much. Bernie and Biden numbers have either stagnated or went up slightly in some polls. Although, it could be that the rumors of Biden running are costing her poll numbers to go down a little.
It doesn't really seem that Hillary is trying all that hard to improve her appeal besides some a few speeches, announcing her agendas, and doing that one ad. Other candidates on the other hand are doing much more in getting themselves out there. Her campaign seems more passive than others, and seems to be purposefully like that. But that strategy, it seems, is letting her appeal falter over the months and not addressing the supporters concerns at all. I guess the campaign isn't concerning itself with the media or the would be supporters and other voters yet, but instead announce agendas, raise money, and lay everything out to than campaign on them later. If that is the plan not sure if it is going to work out.