How can I keep my MSDS book up to date and organized?

You're referring to Safety Data Sheets (SDSs), which were previously called Material Safety Data Sheets (OSHA revised the name, required information, and format in 2012). I applaud your desire to have an accurate SDS book, since it's a key OSHA requirement and an important part of a safety program. My suggestion is to compile an inventory of chemical products used in your facility, which is also a requirement under OSHA's Hazard Communication Standard. Make sure you include products used in the office area and those purchased at retail stores. You can then double-check that you have an SDS for each product on the list and can request missing SDSs from the appropriate vendor. [You can download a sample inventory form at https://prnt.in/hazcommprogram.]