You read a book once, why would you read it again? You watched a movie once, why would watch it again?...maybe one would do that again for the sake of entertainment, but would you conclude the second time the same conclusions you had first time?
The spiritual path isnt a linear one, but a spiral path...the difference is the following: on a linear path one draws a straight line, which means with time new things should arise on your way.
While one spiral path, one grows consciously, and one returns to the same points as he spins around and rises up, i.e., you read a book now, and in two years if you read t again new understandings will pop up to your mind, new angles you didnt see through, new perspectives you developed let you see things differently.
So it is wise to read books or novels you read when you were a teenager, or watch a movie like avatar or matrix...you will see differently...
Enjoy every second of it...