How do I remain logged in to a website when downloading webpages using wget

I am using wget with the recursive option to download part of a website. To enable me to download directories and files that are only avaiable to logged in users I am using the --load-cookies option.

This works fine for a while. But after some period of time the session will expire and I will start getting 403 errors for the protected pages.

How can I solve this issue?

Ideally I would like to tell wget to re-login periodically, but I don't think this is possible whilst the command is running.