A great story is not written once, it is re-written. Writing a story is a process of revision - characters, plot lines, worlds changing
with mere keystrokes. When writing, one must allow the story to develop and cultivate, if the story prematurely stops, it loses energy.
Next time, you are at the keyboard, take a deep breath: cut, trim and refine sentences. Place the edits in a special folder (you may use the sentence(s) again somewhere else.) Allow the story to blossom to its fullest potential. You’ll be amazed at the results!