Using the 1.09.4 palette (AKA the Doom palette), extract the sprites. Then, using the new palette (Either by making the new IWAD the 2.0 wad, or just manually loading in the pallete), switch to that palette (Click on it, and in XWE, click "use current" in the palette menu. I dunno about SlumpED), then reload all the sprites. They'll be converted to the new palette, but there may be some errors here and there. In those sprites cases, you may need to do it manually in MSPaint, or Paint.net preferibly.