IP management

Our company has 500 users with static IPs. I’m tired using spreadsheets and numerous notes from our admins to mananage IP lists. We’re 6 sys admins and every time we bump into a problem that the IP lists are not updated.
Does any one have a simple IP management program with central repository dB?
Or how do you manage IPs in your org?
Please email me at ustek@hotmail.com
Thank you.