ExitAustralia
1. Exit
An exit is a designated route or point where traffic leaves a road, motorway, expressway or other major route. On high-speed roads, an exit usually leads from the main carriageway onto an exit lane or ramp that connects with another road or destination.
Drivers approaching an exit should follow the direction signs and road markings, move into the appropriate lane in good time and adjust their speed as necessary after leaving the main traffic flow.
What should you do after missing a NSW motorway exit?
Continue to the next exit.

Traffic rules
Australia