A device for repositioning an implant within a lumen of a subject including (a) a catheter having forward and rearward ends and a collapsible and expansible stop element mounted adjacent the forward end of the catheter, the stop element being adapted to engage a wall of the lumen when expanded and to provide one or more passages extending from a rear side of the stop element to a forward side of the stop element when the stop element is expanded and engaged with the wall of the lumen and (b) one or more snares, each snare having engagement features, the stop element and the snares being constructed and arranged so that the snares can be positioned extending through the one or more passages with their engagement features forward of the stop element.