We have a pair of reading glasses and one lens keeps falling out.  It
was taken back to Wal-Mart (yes, I know, but it was convenient) and
they did something that worked for a while, but it is popping out
again.  There are no screws or even a well defined grove, so I have to
assume they were glued in place.  Can they be re-glued?  If so, how
(so as not to damage the lens)?  Other ideas (besides getting another
pair because I'm told the frame style is not available - and we know
how important style is).

Thanks,
Dave