There is a glitch that will totally throw this idea off. It's what I'm going to call "The Saving Bug". Say you get your leg chopped off (the most annoying thing in the game) on level 17. You would be very mad, simply exit to menu, and click on whatever you were doing (Story or Endless). Doing this puts back everything that happened since you were last in the room with upgrade bot (except for clones). This allows you to scout out the next mission almost carefree. Say you end up like the black knight (If you got that, you're awesome) with an arm and a leg chopped off. Do that and you'll come back fine with full repairs. I think this bug should get patched and maybe add an upgrade that heals all damage done to your drone/clone-of-a-drone. This upgrade would NOT have a max limit. As it simply puts back that leg that Mk:2 Jetbot stole from you.