The application specific and useful in this case is not an application with GUI, but a service instead. You need a service to be always running that controls and looks for the location of the user. Metro applications don't have services, they only have background tasks but that will always throttle the system.
In the light of above paragraph, what you need to create is either a metro application that has background tasks and continues to listen to location updates, Jerry Nixon mentions that,
As for background tasks, their activity is constrained identically to a metro app and limited to a single CPU second every 2 hours (there is one exception).
Would this suffice?
Otherwise, you would need to program a real Windows Service, that would control how location changes, Windows Runtime APIs can be used to program that, I haven't yet done that but I am sure this would give you a time-to-time update and control over where the user actually is at the moment.
Walkthrough: Creating a Windows Service Application in the Component Designer[
^]. You would require to install them separately.