Jim, I hate to tell you this but you're probably going to be replacing the DPF soon. Been there, done that.
Another option would be to take it to a local company that cleans DPF's off the big trucks. Only trouble is that our DPF's aren't designed to be cleaned, and they will have to cut the ends off the DPF in order to do it. After cleaning, the ends can either be welded back on, or a flange kit can be installed that will allow easier cleaning in the future. But...........if your DPF core is cracked, melted, or has too many cells permanently plugged, it's new DPF time.
I know, it's not pretty. Unfortunately, what you are experiencing is the biggest reason I don't own the truck in my sig any longer. I loved everything about it except the DPF and regen behavior.
:):)