Part of the commission that God gave to His disciples to get people baptized. It is one of the exercises that is important for a christian to undergo. It is not something that we do casually without seeing the significance.
When we come to Christ in sincere repentance, baptism is expected to follow. During the early ministry of Jesus' disciples after He ascended to Heaven we observe that after the disciples preached the gospel to people they got the people baptized. There is one Lord, one faith, one baptism according to Ephesians 4:5.
This shows that baptism is meant to be an conscious decision we take, not something done over and over again.
Being baptized twice does not make our faith stronger. Bible never really recorded anyone being baptized twice during the time of Jesus disciples.
What truly matters is the condition of the heart. If a believer goes astray after baptism, the solution is repentance and undergoing another baptism. Our walk with God is sustained by daily obedience, not repeated ceremonies. God is more concerned about transformed lives than we doing the same thing over and over again.
Romans 6:4 enlightens us that we are baptized so that we may walk in newness of life. That new life is proven by how we live, not by how many times we enter the water.
When baptism is done the right way it does not have to be repeated. What we now have to do is the live our lives with the consciousness of what baptism truly represents and also honour God by living a life that is in total surrender to His will.