Shell Lite – Updating from 1.4.5 to 1.7.0 critical?

My site is using a child theme of the Shell Lite theme.

The Shell Lite theme was modified by someone else.

I’ve found that if I update the theme, my child theme is lost and my website reverts back to the look of the Shell Lite theme.

So I’m wondering if I even need to be concerned about updating my theme. Are there any security or other major concerns?

I don’t care about any new Shell Lite features.

Please let me know if I can just leave my theme as-is or if this is there is some critical reason I need to update.

Thanks.