Custom Course Progress Marker

Hello all, 

I have built a progress meter that allows users to see how far through a course they have gone/to go. It uses the system variable Project.Progress to change the state of an icon. This all works perfectly. 

HOWEVER I also give my users an option to completely restart the course. I do this by providing a Project > Restart Course trigger. This, however, does not reset Project.Progress and therefore the Progress meter shows the furthest point reached rather than the current progress. I tried rebuilding this with Menu.Progress no difference. And also adding another trigger to reset the variable to zero but this seems to have no effect. 

I suspect this is due to not being able to do anything other than read the system variables and/or something I am unaware of happening in the background. I really don;t want to create a variable that manually keeps count of the slides especially as my slides can be revisited many times. But I cannot think of how to repalce the Restart trigger.