Resume last waypoint after AUTO mission interrupted

Is it possible to resume the auto mission after it is being interrupted by RTL. I am using Pixhawk 2.1 with here GPS.
Or are there any changes to be made to make this possible.
Please help!!!

Seems this parameter is what you need.
http://ardupilot.org/copter/docs/parameters.html#mis-restart-mission-restart-when-entering-auto-mode
But usually RTL cannot be break ,unless you change the flight mode.