How about automating the entire process? The Perl module Net::Google::Spreadsheets::Spreadsheet seems like a possible resource for automatically getting the cells from the Google spreadsheet. I haven't used it so I'm not sure if it's up to date. Start with a simple test version of what you need to do and build it up to the requirement you described. For your more complicated requirements create other versions. Through experience and refactoring you could perhaps combine the scripts at some point.

See also: API::Google, Net::Google::Spreadsheets::V4, and Net::Google::Spreadsheets::Worksheet