What you could do is send itself a Disable input OnPlayerTouch. The player still gets his health/ammo and the kit is removed from gameplay. You could also have the item send itself an Enable imput after a delay of x number of seconds OnPlayerTouch to make it "respawn"
ETA: Adding a delay is easy. On the Output tab, you'll see the fields like My OutPut Named, Target this Entity, etc. There's a box labelled After a Delay of [___] seconds. This means that whatever output this entiry sends, it won't happen after the specified time has elapsed.