You might also peek in the Option Name Manager and you will notice there are severals neat tools there ...
Add ALL Option Values to ALL products for Option Name
Update ALL existing products that have at least ONE Option Value and Add ALL Option Values in an Option Name
Add ALL Option Values to ONE products for Option Name
Update ONE product that has at least ONE Option Value and Add ALL Option Values in an Option Name
Add ALL Option Values to ONE Category of products for Option Name
Update ONE Category of products, when the product has at least ONE Option Value and Add ALL Option Values in an Option Name
NOTE: Always Backup your database before making changes like this ...