I was gonna do a search, but the search button is gone. I just need a quick answer. I got my Nikky covers back today and they need to be re-waterproofed after two babes' worth of use before my new dd uses them. I can pick some spray from WalMart and spray them, but have a couple questions first. Do I need to prep them at all? And do I spray inside and out or just outside? TIA!