Yes, you should be able to upgrade without problem, assuming your current version is registered to your account and current email address. Simply go to this page. Once there, the advice here is to first install the Trial Version, to ensure it runs without problem on your computer.
Once you are happy that it does you can then return to that page and choose the Upgrade option (at the bottom of the page).
If, by any chance, your current email address is any different to the one registered to your Magix account, post back and we will advise you how to update your account details.