I don't think she was one of the eleven who were killed on the black hawk helicopter. Later, when Mike goes to find Kang and Asher, he kills a couple of people, but I didn't see Lim getting killed at that point. Did I miss something?
She was indeed one of the people sacrificed in the helicopter. This is evident in the scene right before the hostages are led to the helicopter. You see her in the same hooded cloak as all the others, so she was most likely one of them:
In addition to that, you can see that the guy Banning kills when doing the run for the president at the end is not Lim, but the long-haired guy, as Le Phuoc Dai points out in his comment:
search lim Olympus has fallen in Google,look for lim wiki.From there,you know,
Lim was one of Kang's henchwoman and the technical expert of the group who took over the White House . She was disguised as a South Korean government agent when she and the others took over the P.E.O.C bunker. She had killed herself in the helicopter explosion in the North Lawn to stage the death of Kang and President Benjamin Asher , but was discovered by Mike Banning
collected from lim wiki