If you still have the lip, you can superglue it back on.If not, you can MacGuyver a pen cap to glue on. (one of the cheap flimsy Bic ones) You need to split it up the side so you can lay it kinda flat, an then cut your lip design with scissors. Bend it to fit your needs, although smaller works better with this. Leave yourself a tab or 2 to glue to, or sometimes a stub of the "pocket tab" can be used. It wont be like new action, but it will be usable again.