Have a way to save your work without losing the data.
Right now you can't save your work and go back later. it erases everything. can you make it so you can save your work and return to it later? Thanks it would be most helpful.
When you save a map it does save your data and you should be able to load it again with the same map ID. If this is not happening please tell us the map ID with the data that is not being saved.