Completely reset? Sort of. You can reallocate the stat points of a follower in the level up menu(Be sure to spend every point before leaving the menu, in previous versions it deleted those points from my follower). However, if you've only ever given essence in that stat then it won't do anything but reset the other stats. If that doesn't work you can at least level up the breastplate at the smithing anvil in town. Each level on the armor increases the stat which it breaks. So going from level 0 breastplate to level 1 will increase max breast size from 50->60.