Unfortunately, there is no simple way to refresh your existing map. The sublayers of a map service get written to the web map. Thus, subsequent changes to the map service are not reflected in the web map.
Having said that, there is an unsupported tool you can use to look at and manually edit the JSON of the web map definition.
https://ago-assistant.esri.com/
If you compare your existing map with 30 layers to the one with 33 layers, you may be able to copy some of the JSON that defines the tables from one map to the other. While I've used this tool before, I've not tried your particular task. Note, again that this is an unsupported tool and if you make a mistake, you can break your map and there won't be a way to recover it. I'd suggest saving a copy of it and working on that map.
- Save a copy of your web map.
- Login to the ago assistant with your ArcGIS Online account
- Navigate to the folder containing your web map
- At the top of the page, select "I want to view an item's JSON"
- Select your web map in the list of items on the left. Upon doing so, there are 2 sections of JSON that you'll see. One defines the item details card, for example, the name of your web map, description, and tags. The second section of JSON is the actual definition of the web map. This is the section you can edit.
By comparing your web map with 33 layers, you might be able to see the difference in JSON and copy that to your existing web map.
Mike
