I was wondering about an update that I have for

I was wondering about an update that I have for the Marketpress Add On plugin. It has a link to 'upgrade to update' and when I click it, it takes me to the Marketpress plugin page. I'm not sure if I have to download Marketpress again?? I have configured my website and ironed out many kinks so I just don't want to lose any of the work that I've put much time into. Any info or help would be great!