You should not need to re-treat your entire tarp, but you might find a spot or two that you would like to re-seal. Martexin refinishing compound is from the folks who made your oilskin, so it is the same compound used in the first place. We sell it, but you can buy it from any number of online retailers. Just take a little bit in your fingers to warm it up, then rub it into your tarp. That's it!