Hi,
Create a new app, it will show up. You can then go into the app\##\configs\AttributeTable\config_Attribute Table.json...
you should see a new ID for that layer. GO back to the original app file find that layer name and update it with the new ID.
I dont see why this would break the service though, unless you have schemaLocked = True on the arcgis Service. Or the schema changed...
But then I should be asking important questions, such as ... is this Web app developer or Web app in ArcGIS Online.?