To fix your new game required issue, when you add/make a new variable keep track of them. Create a "save update" button in the bedroom or somewhere else, where it goes through each one of the variables and checks to see if they are set to null or "" (you might have to check for both.) and if they are set to one or the other just set the new value to 0. Problem solved. Otherwise include a new playthrough save up until the new content.
Otherwise it's too big a chore to replay from scratch since the checks you've got in the code for checking if thresholds have been reached get broken by cheats... (or you could just create a "skip to" button that gets everything to the current state. You have some options without requiring everyone replay every single time.
