Create a database in MySQL. Make a table called ip_tracking with two fields: ip_address char(15) and last_visit which can be a date type.
When the page is loaded, check to see if the ip_address is in the table. If not, put it in and set the date to now().
If the IP address is in the database, check to see if the last_visit was today. If so, then print a message that says, "Sorry, come back tomorrow". Else display the content of the page AND reset the last visit to today.
Be aware that it's very easy to use proxies and to switch computers to get around this sort of thing. Also be aware that you will occasionally block people who should be allowed to access the page if they share an IP with someone who visited the site today.