Once a graphic starts peeling, forget about trying to reapply any edges, which have already lifted. The adhesive on these peeled edges have most likely been contaminated with dirt. Edge lifting isn’t the end of world, though. In many cases, you don’t need to go through the time and expense of removing the entire applied...
http://supply55.com/blog/2013/11/how-to-fix-edge-peeling-vinyl-graphics-2/