With fiction, the first draft is the only living draft. Second and later drafts invariably kill the story little by little. So the discipline of writing is to let the language flow in the first draft as fluently as your speaking, as if instead of writing it you were telling it aloud to an eager audience who believe in and care about the same stories as you.
If you find that you have made a story mistake somewhere, you must go back and write a new first draft from that point onward, not looking at or trying to salvage any of what you wrote before. Editing, on the other hand -- fixing spelling and typos and resolving inclarities -- does not count as a second draft, any more than picking up litter from the highway constitutes road construction.