When you repent, you surrender your serpent seed, which is your human will. This means death to your human will. Just as a physical body must be buried when it dies, your human will has to be buried also.
This is why there are those who say that they have repented but still do their own will. That is because their human will did not really die, it was not really buried six feet under the ground. Their human will came out of its grave to do its own will again.
Repentance is death to your human will. When you repent, you surrender the serpent seed, you kill the serpent seed that is within you.
Baptism is burial of your human will. So after death, you have to be buried through baptism in water.