Give her 2 (or even 3) orbs as usual. She can dismiss once without a kill, but if she does she cannot dismiss again in that round, she can heal up, unless she's in Ult.
I think this opens doors for many plays as you can take duels and dismiss away even if you do not get a kill at the expense of not being able to do it again.
Another idea :
Same as above but, she can dismiss once without killing and it takes away 50 or 75 HP.
So you can selectively choose whether to commit to a gunfight, or lose 50-75 hp reposition and then duel them to fully heal yourself.
Any thoughts?