You can use Element Visibility to bring back deleted elements from smaller breakpoints.
For example, let's say you have an image that you accidentally deleted on your Mobile breakpoint.
To bring it back, do the following:
1. Go to larger breakpoint that still has the image
2. Select the Image Element
3. Open Properties Panel
4. Scroll to Element Visibility
5. Re-select the Mobile Breakpoint
6. Go to Mobile and see your element!
Watch the Gif below to see it in action: