Do you order the same items/products every few months?  There's a simple way to do this from your Account at

LOG IN to your account at 

From there, simply click on Completed Orders (left menu bar) and find an order that contains the items you need to reorder.  Click on the blue Order Details button.  

From this Completed Order, you can simply check the items in that order that you would like to Reorder and click on the blue Reorder Button.  These items will be placed in your cart immediately.  And from there, you can easily continue with the checkout process.