You can place the focus on Jesus Christ when explaining why it is necessary for us to have these repeated warnings in the Bible. The warnings need to be heard, but they must always be heard in the context of the gospel. When speaking of God's promises, you have a chance to spend time explaining what Christ has done.
1 Hear this word that the LORD has spoken against you, O people of Israel, against the whole family that I brought up out of the land of Egypt: