How to update the news theme?

I see that the new version of this theme have been released. How can I update it?

It depends if You have made any changes to current theme beside editing override.css.

Yes, I did. But I can make those changes again after updating the theme.
So, how to update it?

I would suggest to back up old template folders, then upload new one in place of the old one.
Or You can download theme to your localhost first, do all the changes and then upload new one in place of old one (its easiest to delete old firstly and then upload new one).
Also remember to replace child theme (and changes inside of it if You have made any).