Something to help both you and your daughter is to give her a clothes budget for one year.
For example tell her that she has $500 for clothes for the whole year starting now or in January. She will have to keep receipts and write down how much she spends, and obviously deduct what she spends.
That way, you are teaching her both money management and to become a thrift shopper herself.
So, if you daughter 'has to have' that brand new outfit from Justice and it is $70 ... she is making that decision even if she may not have enough next winter to buy a new coat.
Then you can relax and not worry about looking for sales, etc