refreshing pages (html/php mix)

I am having a problem with setting up page refreshes properly in my situation... Here's what I've got, hope I put it in text as well as I have it in my head

I originally had my pages all set to refresh every time they were hit (because they're completely mysql driven with new content all the time, I didn't want to be showing old pages)... but on some pages, this format didn't work. When I have a form, for example, and they submit the info, if they do not fill it out correctly, it gives them an error, and tells them to hit back in their browser... but when they were going back, all the info they just spent 10 minutes typing was gone.. Removed the refresh (the form content didn't change, so I didn't need it there) and the page works fine (they make an error, they back up, the info is still there). That was the easy part.

Now, I am building a cookie system that recognizes the user and his password when he's roaming the system so that he doesn't have to keep entering his name and pw every time he enters information on the form (much like UBB here, you enter your username and password once per session, and it sticks around till you close the browser). Now my problem : The user goes to the form once, enters name and password, and submits... the information is submitted, the cookie IS placed. They go roaming around the site, then come back to the form again, its the 'old' form, and it doesn't pull in their cookie'd information... so they have to enter it again. If I hit refresh instead, it will pull the page up with the cookie'd information in place.

To sum it up, is there a way to make a browser not refresh a page if your coming from the same page, and refresh if coming from anywhere else?

(Before the flames of off-topic posting fly, I posted this here because the site is built on php/mysql... even though I ended up not making any php references here... sorry )

Mike