Reinstalling the OS just because you lost a file? Just install the package. Or copy it from a live CD. Or another ubuntu installation. Or compile your own perl. Or, gasp, restore from backup.
I think on Debian (and thus Ubuntu), apt-get and some other system-relevant programs still rely on /usr/bin/perl working. This would mean that installing any package likely won't work on that system.
I think that Debian plans/planned to remove the dependency on perl for apt-get, so maybe that will work in a recent version of Debian/Ubuntu. Restoring from backup would be the approach that's more likely to work.
If apt-get depends on perl, maybe the lower level program dpkg doesn't.
Downloading the .deb package manually then installing stuff with dpkg -i $deb_file has helped me to repair some Debian systems where apt wouldn't work anymore.
Perl 6 - links to (nearly) everything that is Perl 6.