2.79 vs. 2.8 F6 key to recall menu When I add a new shape a context window shows up with some useful settings to the new object, but as soon as I move or pan, or even accidentally, such additional menu disappears. 

In the 2.79 Blender I used F6 key to recall it.
How about the new release?
The shortcut is F9 or you can access it through Edit &gt; Adjust Last Operation.

Quoting from the Manual:

After an operation is complete you can tweak the parameters of the operation afterwards. In editors that support it, there is a “head-up display” panel in the bottom left based on the last performed operation; dependent on mode and context. Alternatively, you can create a pop-up with F9 which does the same thing.