Lots or Regens and bad fuel milage

[Joe2052]

I have a 2013 KW T660 with a 485 ISX15 engine with 900K. Last couple of months i have been dealing with a significantly reduced fuel mileage and the engine regens every 8-12 hours. I have replaced the 7th injector, the dpf filter, changed out all the sensor and O2 sensors. I even replaced the DEF filter recently. Anyone else deal with this issue and get it resolved. I have no idea what else i can do.