Destroy session, but keep one variable set

Question

I am using session variables to control logins and page access. I use variables to control different user groups that a user belongs to, so I have quite a few session variables.

I also use a session variable to remember the users last visited page upon refresh.

When the user logs out, I use session_destroy(); to remove all variables. What i would like to do is to maintain the last visited page variable even after the user has logged out.

I think I could do it by using the unset function on every other variable, but there are a lot, and was wondering if there was an easier way?

Thanks Eds