You can use the accelerator pedal to increase speed in the normal way, for example to overtake another Audi A3. Once you release the accelerator, the system will revert to the speed you stored initially.
However, if the Audi A3 exceeds the programmed speed by more than 10 km/h for more than 5 minutes, the cruise control system will be deactivated temporarily. The indicator lamp in the instrument cluster will go out, but the programmed speed will remain stored.