Is a woman obligated to make up the days she fasted due to not verifying her purity by checking the spot, or is she excused by ignorance?

The basic principle is that menstruation persists. So, whoever fasts before ensuring her purity, her fast is not valid, and she must make up that day. This is because doubt about purity prevents the fast from being valid, and ignorance is not an excuse according to the majority of scholars.