This is a common concern. In most cases we are able to carefully remove the original inspection sticker and then put it on the new windshield. The inspection stickers are not designed to be removed and re-used, and so occasionally we come a cross an inspection sticker that is not suitable for removal and re-use. In that case we can either cut out the section of windshield that the stickers are on, and you will be able to use that cut out section of windshield with the stickers on it as proof of inspection, or you can get the inspection stickers re-issued. The entire inspection should not have to be performed.