As a hypothetical example suppose I have a non-orthodox relative, say an Aunt. I see this relative infrequently, say at family functions 3-4 times a year. Each time I see this relative I make overtures to my Aunt about becoming more religious. She has made it abundantly clear that she is not interested, will never be interested, and finds it slightly harassing that I continue to bring it up.
At what point, if any, can a person give up on trying to encourage a non-religious person to become more religious?