Hi Babycody,
While that is a nicely modelled shelves, I have to say it is not modelled efficiently at all. The whole thing should have made up of smaller components instead of this raw geometry.
Anyway, based on the model ("as is" - since I could have found a more logical way of dividing the vertical rack)), I identified a piece that is repetitive in the racks and turned it into a component (Import it into your existing model from File > Import otherwise it will just open as a simple skp file). Since it is 3" high, all you need to do is to add 16 instances of it on top of each other. This can be done easily with a linear array.
If I were you, I would just rebuild the whole thing using these pieces instead of adding though. The same amount of work actually. This would reduce file size big time. Of course, you will need to hide the visible seams at the end (I have already hidden the bottom face and its bounding edges so you should only do it with the top face/edges and put a "cap" on the very top). Turn on hidden geometry (View menu) to be able to work (snap to etc.) to these hidden parts.
Piece.png
Piece.skp
