A device for repositioning an implantable device within a natural bodily lumen comprising: an endoscope providing an outer tube defining a lumen; an inner member adapted for insertion into the outer tube; a grasper adapted to engage an implantable device; and a retrieval hood, which hood is atraumatic and is attached to and fitting over a distal end of the endoscope; wherein the endoscope is slidably mounted around the inner member to advance the atraumatic retrieval hood distally to capture at least a proximal portion of the implantable device when the device is collapsed; characterised by the inner member being an inner tube defining a lumen; by an elongated member having a proximal end and a distal end, the elongated member slidably disposed within the lumen of the inner tube; in that the grasper is disposed at the distal end of the elongated member and is adapted to engage a drawstring of the implantable device to collapse at least a portion of the implantable device when operated; by the retrieval hood being a flared retrieval hood; in that the grasper is adapted to be drawn proximally into a distal portion of the inner tube when the drawstring is engaged by the grasper; in that the endoscope is slidably mounted around the inner tube to advance the atraumatic flared retrieval hood distally to capture at least a proximal portion of the implantable device when the device is collapsed and the grasper is locked in place relative to the inner tube; and by the repositioning device further comprising the implantable device, comprising: a flexible, floppy sleeve, open at both ends, to extend into the duodenum; a collapsible anchor coupled to a proximal portion of the sleeve; and the drawstring, threaded through a proximal end of the anchor and drawn into the inner tube by the grasper; at least a proximal portion of the anchor being captured within the retrieval hood. an endoscope providing an outer tube defining a lumen; an inner member adapted for insertion into the outer tube; a grasper adapted to engage an implantable device; and a retrieval hood, which hood is atraumatic and is attached to and fitting over a distal end of the endoscope; wherein the endoscope is slidably mounted around the inner member to advance the atraumatic retrieval hood distally to capture at least a proximal portion of the implantable device when the device is collapsed; characterised by the inner member being an inner tube defining a lumen; by an elongated member having a proximal end and a distal end, the elongated member slidably disposed within the lumen of the inner tube; in that the grasper is disposed at the distal end of the elongated member and is adapted to engage a drawstring of the implantable device to collapse at least a portion of the implantable device when operated; by the retrieval hood being a flared retrieval hood; in that the grasper is adapted to be drawn proximally into a distal portion of the inner tube when the drawstring is engaged by the grasper; in that the endoscope is slidably mounted around the inner tube to advance the atraumatic flared retrieval hood distally to capture at least a proximal portion of the implantable device when the device is collapsed and the grasper is locked in place relative to the inner tube; and by the repositioning device further comprising the implantable device, comprising: a flexible, floppy sleeve, open at both ends, to extend into the duodenum; a collapsible anchor coupled to a proximal portion of the sleeve; and the drawstring, threaded through a proximal end of the anchor and drawn into the inner tube by the grasper; at least a proximal portion of the anchor being captured within the retrieval hood. a flexible, floppy sleeve, open at both ends, to extend into the duodenum; a collapsible anchor coupled to a proximal portion of the sleeve; and the drawstring, threaded through a proximal end of the anchor and drawn into the inner tube by the grasper; at least a proximal portion of the anchor being captured within the retrieval hood.