Do you know what a Lapsi is?
It is a Latin word used to refer to persons who have lapsed from the practice of the Catholic Faith. (Lapsi is a collective plural. Singular is lapsus for a male and lapsa for a female.) If you do, you might want to consider joining St. Monica's Sodality.
The home of St. Monica's Sodality is St. John Cantius Church in Chicago, Illinois, USA. The Sodality meets weekly for their Novena Prayer and Mass.
The purpose of the Sodality is to support its members to cooperate with St. Monica in praying for their loved Lapsi.
Here is their prayer:
Exemplary Mother of the great Augustine, you perseveringly pursued your wayward son not with wild threats but with prayerful cries to heaven. Intercede for all mothers in our day so that they may learn to draw their children to God. Teach them how to remain close to their children, even the prodigal sons and daughters who have sadly gone astray.