If you're looking for a solution in Perl, File::Pid might be what you want - it gives you a file with the pid of your server process which you can then use to check.

Personally, I use a shell script to check/start services:

#!/usr/bin/ksh
# Should work with any other shell too
if [ ! ps -aux | grep "/home/corion/myservice.pl" ]; then
    echo "(Re)starting myservice";
    exec /home/corion/myservice.pl >/dev/null
fi
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