How can a Muslim woman regain the sweetness of faith and closeness to Allah after having lost it due to being preoccupied with worldly pleasures, despite her attempts to return and her commitment to acts of worship?

The feeling of shortcoming is a good thing, because it prevents one from falling into misguidance. One must search for the causes of the shortcoming and remove them through sincere repentance and regret for the neglect, then follow the means that aid in steadfastness in religion and increase in faith.