In chapters 12-17 John recounts in his gospel the words and actions of Jesus in the week leading up to His crucifixion.  In these chapters Jesus is highly focused on preparing His disciples for the day when he would no longer be physically present with them.  He does this by repeating certain truths over and over.  Themes such as belief, prayer, the Holy Spirit, obedience, and servanthood come up multiple times in these chapters. He repeatedly emphasizes these truths because they are the foundation of the Christian life and are key to His disciples completing the mission that He leaves them with and are thereby key for believers and the church. 

Take a minute and follow with me in your Bible how the theme of love repeats in these chapters.  Three times (13:34, 15:12, 17) in these chapters he commands them to love one another. Jesus does not leave them in doubt about what this love looks like. Loving Him means keeping His commandments (John 14:15, 23, 24).  Love for one another means loving one another as they were loved by Him (13:24;15:9, 12, 13).  He tells them that this is important for a couple of reasons.  If they love one another the world will know that they are his disciples (John 13:35) and it is in the sphere of this love that they will abide in the fellowship of the Father and Son. It is in that fellowship that the Holy Spirit is released in them to produce God glorifying fruit in them (John 14:21, 23; 15:15:10). It is also this love for Him and for another that keeps them in the wonderful unity that Jesus prays for in John 17 that reveals to the world that Jesus is sent of the Father (John 17:26).  When we find that we are not fruitful and that our life isn’t impacting others as we might desire it could be that the problem is a deficiency in love.  Loving as He taught us to love must be a primary emphasis in our lives and in our churches if we are to be fruitful in our lives, our mission and in glorifying Him.