[Esaias]

In that He died, He died to sin ONCE.

Repenting after backsliding means you return to honouring your baptism. Otherwise it's like saying you took the Lord's name in vain. Repenting of that means honouring the vows you took., not making new ones.

A man who cheats on his wife, if he repents, doesn't remarry his wife. That would be a repudiation of his original marriage! Instead, he honours the vows he originally made.

This assumes his original dunking was a valid baptism to begin with.