There are 2 types of regen, active and passive. Passive is when you have enough of a load on the truck where the egt's are hot enough to keep the filter relatively clean. I mostly travel unloaded so I usually regen in the active phase. This is where you get the "cleaning exhaust filter" message and notice the power loss and boost recirculation. This active phase is where the fuel is introduced into the exhaust to "clean" the dpf. Now I've had my truck for 2 years, job 1, when it went into active regen it was very noticable meaning the first few times it initiated I thought something was wrong. I have the latest reflash on that recall and its seamless and the only reason I know I'm in active regen is it says it now on the dash.
Now Ford claims its only a 25hp reduction when active regen is going on. We have a 350hp engine....25hp doesn't sound bad, but I'll tell you before the latest flash, it seemed a hell of a lot more than 25hp. I dont have a dyno so I cant provide #'s.
To get back to the origional question about no regen... is your truck loaded often if so, you might just been lucky to have enough passive regen, if not the others are probably right, you might want to get it checked. I believe that since job 2's the message is displayed on the dash.