“The Dean” is flying without radar here. It’s hard to answer your question without knowing where you’re applying and exactly how much below the median at these places your “on the low side” ACT scores actually are.
If you were a junior, I’d say that you should definitely wait to retake the ACT before applying. But your “Ask the Dean” form indicates that you are a senior, and so the clock is ticking. If your top-choice colleges have Rolling Admission and if they accept fewer than about 70 percent of their applicants, then you don’t want to lose out because you applied too late. Instead, send your application NOW but also email your regional admissions rep. (This is the staff member who oversees applications from your high school. You can get his or her name and contact info from the school’s Web site or by telephoning the admission office.) Explain to the rep that you are retaking the ACT and are hoping that your file will be reviewed after the new scores arrive.