Great ideas, but shins, please be aware that some of these more psychological approaches will cut deep, and should never be used as part of play.
A sub is very dependant upon her Dom, and she will feel completely broken if she does not 'feel' as opposed to just 'know' that you still love and care for her, and it is her behaviour and not her which you disapprove of. Don’t rely on the fact that she must know it because of x, y and z; at such times she is likely to be aware so acutely of how much you mean to her and there will be voices inside her head saying that you are rejecting her.
Please make sure there is clear closure after the event, otherwise it can be damaging to your relationship.
cariad