I would contact the manufacturer if they are still in business and ask them about replacing the down. I know that Marmot will wash and replace down in their bags at a very reasonable cost or over stuff a bag to increase its temp rating and I would think that some of the others may as well.

As far as I know, dry cleaning will ruin a down bag or jacket because the dry cleaning fluid strips the natural oils off the down. I take my bags to an outdoors shop that sends them out for washing.