Typically, when your objects started to not dry well with the same setting or increased drying time,
Clean the Air filter
It is a sign letting you know that it's time to clean the filter piece. The filter is the "F" you see located on the bottom of the base unit. Slide it out of the unit, use a brush and water to clean all the dust on the filter and this should solve the issue right away.
TIP: It is always a good idea to clean this filter piece every other month to maintain optimal drying efficiency.
Double check the set Drying Time
Also, you may have changed the drying time by accident, here's how to reset drying time.
Press AUTO > Press DRY until you see your desired drying time > the new drying is now set.
Press DRY until you see your desired drying time.