Must one repeat the Dhuhr, Asr, Maghrib, and Isha prayers if the brownish discharge (al-Kudrah) appeared after Dhuhr and continued until after Maghrib?

If purity is attained after sunset, then the woman is only obligated to perform the Maghrib and Isha prayers, because their time overtakes her while she is pure. As for the Dhuhr and Asr prayers, they are not obligatory upon her because they passed while she was menstruating, and any brownish discharge during the time of menstruation is considered menstruation.