' ... as many as received him, to them he gave he the right to become the children of God' (John1.12 RV)

He becomes your Father; you become His child.
There is a relationship between you which can never be undone. This does not mean you become perfect overnight. You still sin however hard you try not to.
Well then, what happens if I sin ?

A boy, playing cricket in the garden, smashes a window. He has been told not to play there. He keeps out of the way. At mealtime there is an icy silence, for he has disobeyed his father.
This lasts until he owns up and says he is sorry.
The relationship has not changes, he is still a son.
His father could disown him, but he never ceases to be his son.
It is the friendship that is broken, until the boy says he is sorry.

When you disobey Christ, or are thoughtless or lazy, when you do, say, or think, something you know to be wrong, you are still a child of God; the relationship has not changed, you do not have to ask Jesus Christ into your life again. You have spoiled your friendship with Him and it is up to you to say sorry.

Listen to what the Bible says:

'If we say we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins [i.e. say we are sorry] he [God] is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.' (1 John 1.9)