A good exhortation from Mark in Faith To Keep Praying For Your Unsaved Children. It ends:
Don’t stop praying for your children. Don’t give up. God hears our prayers for our children and grandchildren. He desires their salvation more than we do. If Jesus saved you, you have good reason to believe he intends to save your children as well. Pray that he will save them for his glory. Don’t rest satisfied until you see your children saved. And when he does save them, KEEP praying for them!
Read it all here (even if all your children are saved).