What does AI do after it kills target

What I did here in my code is check whether or not my AI’s target health is above 0 if true then the AI will chase that target if false then what do I do? When the false executes my AI stands still and ignores all enemies that are in front of it. Sometimes it sees something but most of the time the sight ignores all targets that is my problem I want the AI to lose sight of its target when the target dies so it can see other targets out there.