The control is looking for a specific water level as the unit drains out. If the pump is blocked or not functioning well, cycle time will be increased. Using non-HE detergents will also increse the wash time by causing a suds-lock in the pump.
A motor control board which is beginning to fail may also increase cycle time by not ramping the motor up to the expected speed during spin. There is a tech sheet in the unit to help you behind the lower panel.