Jeremiah 31:3  The LORD has appeared of old unto me, saying, Yea, I have
loved you with an everlasting love: therefore with lovingkindness have I drawn
you. 
     God has a history and a way of bringing restoration and forgiveness to those he loves. Notice in the selections that follow that God is seen as the Father of His people.  
Jeremiah 31:7  For thus says the LORD; Sing with gladness for Jacob,
and shout among the chief of the nations: proclaim, give praise, and say, O
LORD, save your people, the remnant of Israel.
Jeremiah 31:9  They shall come with weeping, and with supplications
will I lead them: I will cause them to walk by the rivers of waters in a
straight way, in which they shall not stumble:
for I am a father to Israel, and
Ephraim is my firstborn.
Jeremiah 31:12  Therefore they shall come and sing in the height of
Zion, and shall flow together to the goodness of the LORD, for grain, and for
wine, and for oil, and for the young of the flock and of the herd: and their
soul shall be as a watered garden;
and they shall not sorrow any more at
all.
Jeremiah 31:13  Then shall the virgin rejoice in the dance, both young men
and old together:
for I will turn their mourning into joy, and will comfort
them, and make them rejoice from their sorrow.

     God is always receptive to those who have fallen away. I have had people ask me before if God will forgive backsliders. I think the answer is clear from the beginning of Genesis.  
Genesis 3:21  God is seen behaving as the father of the Prodigal Son. He clothed His fallen children. They are still His son and His daughter you see? This is not an angry Father, but a sad Father. He is cleaning up their mess. Yes, we all get into a mess now and then don't we? Even after salvation. But, the important thing is whether or not you turn to Dad for help when you fall.
     Remember Judas? Remember Peter? Both betrayed Jesus. But, Judas hanged himself. Peter cried and clung to the risen Christ. Do you ever hear the word Peter used as a name for betrayel? No, but to be called a Judas is the same as being accused of betrayel. God is perfect and can forgive perfectly before Judgment Day. In the same way, a man on death row can beg clemency from the Governor, up until the moment he is executed. After that moment it is too late.
     Does it crucify Jesus anew for Backsliders to come back to Him? Hebrews 6:4 There is much debate about this passage, but I see a difference between the apostate and most backsliders. Note that the passage is speaking of types of teaching fit for different levels of growth among Christians. Look in Hebrews 6:1 where Paul tells the believers they don't need teaching on repentance and faith, like the Galatians or Corinthians for example. They have been in the church for some time. They were Hebrew converts, and not Gentiles. They needed the teaching he names in Hebrews 6:2  specifically: the doctrine of baptisms, and of laying on of hands, and of resurrection of the dead, and of eternal judgment. He explains that you can't teach backsliders to repent or have faith. They have been there, done that.
     It takes something else altogether to bring a backslider back to Jesus. They have willingly turned away from Jesus after knowing Him. The question is, did they renounce Jesus or did they "fall away?" I don't believe anyone who spoke against Jesus would want to come back. But, many people just look around one day and realize they haven't been to church in awhile. Satan leads them out bit by bit; a missed service here, and a Sunday at the lake there. And, sometimes they only became hurt by individual people. They have "fallen away" as Paul says in Hebrews. It is like a woman who has seperated from her husband. She has already fallen into love with her husband and fallen out of love with him again. He can't make her see him for who he is all over again. She will never look at him again and say, "Wow! Who is that man?" She knows him. But, it is obvious she can take him back, and women often do. It takes a conscious decision to receive him back on her part. She has to undecide to leave, or redecide to love him. And, all the while, her act of loving him again will point to the question of why she left to start with.
     In the situation of the backslider, for a backslider to come back to Jesus, His blood is again applied to the life of the re-newed Christian. This points to the crucifixion all over again. Though there are scars there, they can heal with time. But, the backslider always knows he betrayed Jesus... just like Peter. And Judas "went and hanged himself..." Matthew 27:5  But, not Peter. Remember Peter "went out, and wept bitterly." Luke 22:62 One will be in heaven. The other is already lost.