Personally, Kira is one of those characters that have a good story and crappy gameplay. She was/is a Kano and Sonya Clone. Another couple of things great about her is that she doesn't show alot of skin like this ---->
The other thing that is great about her is that she isn't conected to Quan Chi like most characters. (Scorpion,Sub-Zero,Sindel,Shinnok etc..) If she were to come back, I think they should redesign her MKD costume, when I say redesign, I mean update it a little better, not MORE skin. Or HIGH HEELS.
For her moves I think she should just ditch the whole Kano/Sonya movelist.
I think she should be more agile than more characters and sneaky-er in her story. In her original Kira was a spy that sold weapons to terrorists. I think they should keep this, but make it so she creates and builds her own weapons to sell to them so she could create an amulet that lets her manipulate and control energy around her, allowing her to keep the energy ball.
Movelist:
Energy Ball: Kira shoots an energy ball out of her hands that stikes the oppenent.

Backflip kick: Kira Kicks her oppenent in the stomach with one foot and then kicks them in the face with her other one backflipping off.

Dagger Slash: She Leans foward and slashes her oppenent in the stomach with both daggers in an opposite direction.

x2: Kira uses energy powering her attacks x2%
Post more below, I dunno what other moves to add right now, might add more later.

Fatalities:
Black Dragon Beatdown: She Punches them in the face multiple times kicks them in the face and flips over their shoulders and stabs them in the back. She then breaks their arm and pulls their head back slashing their neck. Blood Goes at and on the camera.

Raining Chunks: Kira powers up energy around her hands and charges the oppenents head up and they start to melt (Their face) and she then stabs them in the stomach and kicks their head off and it explodes and chunks come down and their brain falls infront of her. She picks it up and holds it above her head.
Any more ideas?