I create a RecyclerView list with a default layout. I then add one new item to the list and the layout updates to show the new item. I then navigate to a previous activity. W
When you hit back from an activity you are popping it from the stack i.e the activity object will be destroyed. This is explained in further detail here. The crux of the concept can be understood from this picture.
You can look at this to see how you should recreate your activity - and this to see how you should apply that to a recyclerview.