That’s literally the point: he can’t. His apology is useless.
The point of an apology is to acknowledge a mistake and signal that you will attempt to change your behaviour to prevent or avoid that mistake in the future.
A really good apology will also identify the steps that will be taken to avoid the mistake going forward.
I argue that if you don’t or can’t make an attempt to change your behaviour, your apology has no meaning. That is, the apology is not sincere and therefore not useful.