Your passive performance in the last debate was damaging because it reenforced the Republican claim that you’ve been too passive in getting jobs back and in responding to terrorism abroad.
That doesn’t mean you have to “come out swinging” this time. You need to be yourself, and one of your qualities that the public finds reassuring is your steadiness and authenticity, by contrast to Romney’s unsteady flip-flopping and apparent willingness to say and be anything. But you will need to be more energetic and passionate.