Backing up woocommerce theme changes not in the child theme

[shockcover.nl]

Hello members,

For customization on our website www.shockcover.nl we sometimes can't go around making changes in the main woocommerce theme, which overrides the child theme. Those changes get lost when there is a new version of the theme available. Is there some smart way to make an easy backup for this so we wont have to manually keep track of everything?

For example on https://www.shockcover.nl/shop/classic-black we replaced the shop button to the top. Spend a day or two trying to do this without modifying the main theme but whatever we tried, it got overridden in the end.

Thanks in advance!

Mark