Simply go into your material file and change everything to the new preset number. For example, if your preset is currently in folder one, and you wish to move it over to four, simply change all the 1's to 4's. However, to do this quicker, change only the 1's if it's something like "material preset_1bodyMatL" (or, really just the pieces of text found all the way on the left of the coding). If this is confusing, I can always whip up a code for you if you want ^^ (Just say the original preset folder name as well as the folder you wish to move it to)