There are a few things you can do to keep advancing. The easiest is to pick up some good books about programming that aren't necessarily about a particular language. "Code Complete" and "The Pragmatic Programmer" are two excellent books for that.
Another thing you can do is start learning different types of languages. Learning a more object oriented language like Ruby (or even Java) can do wonders for teaching what OO is really about and can help you better understand why Perl's OO is "bolted on the side". Learning a logic or functional language can also help you learn completely different ways of looking at problems. These will make you a better programmer in the long run.
Cheers,
Ovid
New address of my CGI Course.
Silence is Evil (feel free to copy and distribute widely - note copyright text)