You can do this already with cPFence FWIW. Manually of course, but could be easily done with a weekly cron job.
`cpfence --bulk-del-wl-ip URL_OR_FILE Bulk Delete IPs in URL/FILE from whitelist.(e.g., cpfence --bulk-del-wl-ip https://a.com/file.txt )
cpfence --bulk-del-bl-ip URL_OR_FILE Bulk Delete IPs in URL/FILE from blacklist.(e.g., cpfence --bulk-del-bl-ip /PATH/TO/FILE )`
