I have been using UBCPFs for 4 months now and they are not nearly as soft as they were when I first started using them. They're not ultra stiff, just feel kinda hard. I do a cold prewash with 1/4c. detergent and then a hot/cold long wash, sometimes adding vinegar. It almost feels like there is still detergent in them when done drying. Any suggestions on what I can do to make them soft again?