you can make it so the trip wire is floating and then put the red block behind the wire showing the user should shoot there. This way the trip wire will be floating, when the arrow passes by it will trigger it for a second (so a pulse) it's harder to hit the wire like this though. I'm not sure exactly what your looking for though so if you could explain more ill be able to try and help.

like make it reset?
the manual way would be go over and pick up the arrow, as for an automatic way not sure ill see if i can think of something.