Quick and dirty, but not necessarily correct and elegant solution would be:

1. to store some special string like "THE_END" as the last one in the array
2. if the array changes, to open up the Perl script itself, read it line by line, and when you come across "THE_END" (your array end), substitute that with $new_string.", "THE_END" (or basically, concatenate "THE_END" to the new string and then append the whole string to the array
3. save the file

I know, I know, inefficient and quite dirty, but if you need it real fast (besides - of you need it really fast with no downbloadable modules available, like your computer is not online at the moment), that should work.