Copy items in my map to use in another map

Dear,
I wanted to copy the items that I have in a map to paste in another new map.
Or what is the same: finish and save a map but continue working on it and adding things in a new map.
Thanks in advance,

Export to GeoJSON and then import it to an other map in GeoJSON.

GeoJSON includes all MapHub specific things, images, icons, etc.