"What benefits does Baptism confer? Baptism works forgiveness of sins, Delivers from death and the devil, And gives everlasting salvation to all who believe what the words and promises of God declare." (Luther's Small Catechism).
These benefits, young people, we have received in our infant water Baptism. They are great and eternal benefits, made true and effectual by the Holy Spirit through the Word preached to us in our Baptism. Hold fast to the promise given by Christ in your Baptism, and know that what He promises, He will perform. Namely, He will incorporate you into Christ with all His benefits named above, and will also raise you, sinless and holy, unto eternal life at the fast-approaching last day! The gospel preached to you in your Baptism is in full force yet today. If any have strayed into sin and fallen from faith, only repent and all these benefits are again yours to the fullest.
To be re-baptised is only to prove one's unbelief.