Well, seeing as it is a "man-made construct" (thanks wc), and doesn't exist on earth, why would you expect to find it in heaven?
The term "prevenient grace" is certainly a term which a man came up with. It describes, however, a bible truth.
The truth is that "the Holy Spirit exerts influence on the consciences of men apart from the Holy Scriptures. Paul says that "the law of God is written in the heart of every human (Rom 1:19; 2:15); and that God has never left Himself without a witness (Act 14:17). Therefore, it is the grace of the Holy Spirit that prepares the heart of a man who is helpless in sin.