What is the ruling on prayer for a woman who became pure for fifteen days, then had a discharge of blood after thirteen days, and must she make up the missed prayers if she is Hanafi, and is it necessary to change clothes for each prayer?

The determining factor in menstruation is the discharge of blood, not its timing. Therefore, whenever a woman sees menstrual blood, she must refrain from prayer and fasting until she becomes pure. There is no legal text that specifies a minimum or maximum duration for menstruation, nor for the period of purity. Those who have set such limits have contravened the Qur'an and Sunnah. The correct view is that whenever blood appears, it is considered menstruation, regardless of whether the interval between it and the previous menstruation was long or short. If blood appears thirteen days after the previous menstruation, it is considered menstruation.