Yes, you can replace a GoShelf with a new GoShelf. You cannot replace other stone corner shelves with a GoShelf without removing tiles from your walls first. To replace an old GoShelf with a new one start by protecting the surrounding surfaces and wearing safety glasses and gloves. Next you need to carefully hit the damaged shelf with a hammer on the top and bottom of the shelf starting with light taps to harder taps until the shelf starts to break apart allowing the pieces to fall into a box.  Try to hold or place the box as close to the bottom of the shelf as possible so that the broken pieces fall right in and do not fall out possibly damaging a tub, glass, or other tiles in the workspace. Once you removed all the stone pieces, you will need to use pilers to pull the old anchoring plates out of the wall. Clean the old glue from the wall slots with a utility knife, grout removal blade or whatever other tool you choose to best do the job. Next follow the basic installation instructions to install the new shelf.