Diagnosis
Poor drying, especially on a model with a condensation drying system like this one, usually comes down to three things: rinse aid, loading, or a faulty heater.
How to Fix It
Rinse aid is crucial for condensation drying. It lowers the water's surface tension so it sheets off dishes. Check that the rinse aid dispenser (next to the detergent compartment) is full. Set the rinse aid dosage to level 4 or 5 (press the Rinse Aid button to cycle through settings—more bars means more dose). Also, make sure you're not blocking the vent slot at the top of the door with plastic items on the top rack.
If That Didn't Work
The heating element that warms the final rinse water might have failed. You can check this by feeling if the dishes are still warm at the end of the cycle. If they're cold, the heater or its thermostat might be gone.
Heads Up
Plastic items will never dry as well as ceramic or glass with condensation drying. For best results, put plastics on the bottom rack tilted downwards, and use the Extra Dry function which adds a fan-assisted drying phase.