How do I update my theme without losing everything?

I have been experience a few bugs while developing the site.
The developers are aware of these issues and have recently released an update to the theme.
I am near the final stages of creating my site. There are only a few bugs- one with social media icons in the header and footer, and one with my woocommerce product attirbutes.
I am so close to the finish line; I have made changes to various pages/files on the theme.
My concern is that when I update the theme, I will lose all those changes.
Is there a way around this?
Thanks in advance!