There are really two issues in your question. The first relates to the science of acne. It flares in the adolescent age group because of the hormonal changes that occur in that time. It is not caused by dirty skin, though there is a type of bacteria that likely plays a role in the severity of acne, and that is why some teenagers are helped by antibiotics. The first step in treatment usually is benzoyl peroxide and /or retinoic acid cream.
Washing the face frequently is generally not helpful as you suggest, and this leads us to the second issue. Teenagers can be very self conscious, and advice from parents (who they are struggling to be independent from) can be interpreted as criticism. To address both issues, I would recommend making an appointment for your daughter to see her primary physician. Her physician can assess how severe her acne is, explain the cause and treatment of acne directly to your daughter, and set up a management plan that they can jointly agree on. You can be supportive by taking her to the appointment and helping her to get whatever medications are needed.
