You forgot Amazing Grace by John Newton. 😆 As an ex catholic myself, I would say, they might tell you they refill their grace tank, by good works, church membership, receiving the sacraments, praying to Mary and the holy saints, and a host (no pun intended) of other good works. I don't buy it, of course, but those could be some of the answers you might get.
God LAVISHES it on us.
Ephesians 1:3-10 Blessed be the God and Father of our Lord Jesus Christ, who has blessed us in Christ with every spiritual blessing in the heavenly places, even as he chose us in him before the foundation of the world, that we should be holy and blameless before him. In love he predestined us for adoption as sons through Jesus Christ, according to the purpose of his will, to the praise of his glorious grace, with which he has blessed us in the Beloved. In him we have redemption through his blood, the forgiveness of our trespasses, according to the riches of his grace, which he lavished upon us, in all wisdom and insight making known to us the mystery of his will, according to his purpose, which he set forth in Christ as a plan for the fullness of time, to unite all things in him, things in heaven and things on earth.
Romans 5:1-2 Therefore, since we have been justified by faith, we have peace with God through our Lord Jesus Christ. Through him we have also obtained access by faith into this grace in which we stand, and we rejoice in hope of the glory of God.
John 1:14-17 And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth. (John bore witness about him, and cried out, “This was he of whom I said, ‘He who comes after me ranks before me, because he was before me.’”) For from his fullness we have all received, grace upon grace. For the law was given through Moses; grace and truth came through Jesus Christ.
EVERY. SINGLE. PERSON. on this planet is currently operating under a state of grace. If they weren't, they'd be instantly in the fires of hell, burning for what they deserve. Where sin abounds, grace much more abounds. It's not only the saved who are experiencing grace, but it is the saved who are aware that they are operating under and in it.