Not much is known about little Setepenre. She probably died young, predeceasing Meketaten. In fact, she may have been the first Amarna Princess to die. Neither she nor Nefernefrure are present at the mourning scenes at the death of Meketaten. But, who knows? Maybe Setepenre was too young to be present at such a ceremony, or maybe she was just too young to participate, so she was left our of the scene.
It is likely, however, that young Setepenre didn't live that long. She has almost certaily died before Tutankhaten came to the throne.