I would say that one element of repetition is how uncomfortable Troy is with his world.  This is seen constantly and in different contexts.  The social and economic pressures with which he must cope, the emotional frames of references within which he must fight through, as well as his existential angst regarding death and all that it encompasses are repeated throughout the play.  As part of his characterization, this is brought out in the idea of the "fences" that he seeks to build in order to maintain his own distance from this discomfort, something that is not necessarily effective.  Another aspect of repetition would lie in the presence of how bonds are cut off with people in the drama.  To a great extent , people build fences to block one another off from people who are engaging in self- destructive or painful behavior to others.  For example, Rose ends up cutting Troy off when she can no longer tolerate his affair.  Troy ends up cutting Cory off when their fight becomes intense.  Bono, to a great extent, cuts off Troy when he will no longer listen to his advice as a friend.  It is in this process of isolation  that repetition can be seen.