I'm actually trying to come up with a way to cover up tears in paper. What I was thinking is that you take a new sheet, draw and cut out the exact shape of the thing that got ripped (for example, say you were coloring a boot; redraw that boot, then cut out the shape), and then color in that cut-out shape like how you wanted it before it got ripped (be sure the coloring flows smoothly with the rest of your drawing, though (use the same colors, same techniques, etc. on this cut-out that you used on the rest of your drawing)). Once you're done coloring it in, simply glue it over where the tear is, lining it up the best you can with the rest of your drawing (just be careful, and be sure to smooth it out in order to avoid lumps or anything). I have yet to try it out for myself, but am planning on attempting to fix up my own teared-drawing via this method. Hopefully it works! (*^▽^*)