Is it necessary to repeat purification or prayer if one performs ghusl (ritual bathing) from menstruation with the intention but in an incorrect manner, or upon remembering the mistake during ghusl?

The obligatory ritual bath (ghusl) after menstruation is performed by intending to cleanse oneself and ensuring water covers the entire body. If, during the ghusl, you mistakenly leave a part of your body unwashed, then only that unwashed part needs to be washed. Doubts about the validity of the ghusl after completing it do not have any effect, because a doubt concerning an act of worship after its completion is not taken into consideration.