How can i automate password resets/updates for all my 700+ account logins?

I want to be able to change all my passwords to individually configurable values with just one click.

Is there any software available, or sample code to show how to achieve this? Ever since I started using password manager tools I always was wondering what happens when this data some day needs to be replaced.

I thought a tool for automated password updates would really make sense, maybe with an open plugin api for adding new services. It should be a transparent, open source solution that should definitlely not be web-based (unlike LastPass).