If you ask the ordinary religious person he will say, "Repent -- punish yourself." But Atisha is saying: If you are attentive, that's enough. Be attentive to your inattention, be aware that you have not been aware, that's all. No repentance is needed. Don't feel guilty; it is natural, it is human. To fall many times is not something to feel guilty about. To commit errors, to go astray, is part of our human frailty and limitations. So there is no need to repent.
Repentance is ugly. It is like playing with your wound, fingering your wound. It is unnecessary, and not only unnecessary but harmful -- the wound may become septic, and fingering your wound is not going to help it heal either.
If you have fallen, just know that you have fallen, with no guilt, with no repentance.
There is no need to go anywhere to confess it, just knowing it is enough. And knowing it, you are helping your awareness to grow. Less and less will you fall, because knowing will become more and more strong in you.