Lelouch didn't want to kill Cornelia but to take her captive. I get the feeling that the combination of Clovis' and Euphie's deaths shook him so that killing his siblings is no longer his first solution. Though, Clovis had to be killed to show his resolve. If he met Cornelia again, I doubt he would kill her unless he had no choice. I don't think Cornelia will live, but nor do I agree that Lelouch is "after her head." He needs her for information. Otherwise he would not have tried to take her in 25. He would not have set up Darlton for a non-fatal attack.
(no subject)