So, let's have it then!
Have a module that calls in an emergency field repair team. Maybe some sort of automated flying drone. You call it in and it comes flying to you and hovers over your head, and when you power down, it starts repairing your armour. Maybe it repairs like 50% of total max armour. So if you're at 25% armour, it'll repair it to 75%; if you're at 50% it'll repair to 100%. If you're at 0 it'll repair it to 50%.
It wouldn't repair internals, just armour. It'd basically be a Repair Bot, coming to slap some more ablative armour on you.
That it requires you to power down (and leave yourself vulnerable) for a few seconds is a good "weakness".