You can make a patch to to the cone using a thin glue and a layer of fiberglass mesh tape similar to a drywall joint tape. An epoxy as Bill suggest and a small patch on either side would be best. Try to keep the patch small because you dont want a weight build up that will change your drivers specs. Anything you do to repair it will of course change the sound. The question is can you hear the change or is it worth a recone. If you have a 1/2 hour it's worth a try.

Bill