When to date has expired this screen should change to allow free registration update.
This is indeed what has been reported on the forum several times: wait for the expiration quietly, you are (and you will always be) protected until "D" day.
The link number 3 (Click Select in the Avast Free Antivirus column.) is unfortunately not always displayed even after repair (according to other reports), maybe to encourage the user to switch to a paid version
Or, if it's really too scary, a clean installation should reset the countdown (no more registration history , so ...) , I think.