Short journeys with a diesel that has a dpf is a deadly combination for the dpf.
The journeys are not long enough to regenerate the filter.
A longer motorway drive (with high rpms) may regenerate the dpf.
The remapping doesn't make it better. I can't see from here whether or not that has been done correct without risks for the dpf.

Whether or not you have to replace the dpf also depends on the code you read.
What's the number of the code?