Don't give up just yet trying to contact the author.
Ping the author again via email.
Search other modules the author wrote to see if
there's a more current email address.
Try a web search for the author as well.
Give yourself maybe another week after your
best efforts at tracking down him/her.
If you still haven't heard anything by then,
send mail to email@example.com,
or post to comp.lang.perl.modules,
asking whether anyone is still claiming to maintain
the module in question.
If no one in those forums can vouch for someone
currently owning and maintaining the module
(after another reasonable wait,
another week or two),
then you can probably feel free to take over and
upload a new version to CPAN yourself.
If you do, don't take this ownership lightly.
If you're really going to take over,
be prepared to field questions, fix bugs, etc.,
in the future.
If you're not
interested in doing that,
but really just want to make your one fix available,
then at least document the fact that the
ownership is up for grabs,
so the next person in your situation isn't
left wondering like you are now...
(Eric Raymond covered this property/ownership aspect
of open source software in his
Homesteading the Noosphere
essay, which will be part of his eventual
The Cathedral and the Bazaar