@tangoperuYeah, I found that too when I wanted to correct a rather embarrassing typo in a chapter. The only Edit I could find was in the story-stats page, when you click on a chapter, you can edit it's name.
But you don't have to worry when resubmitting a chapter.
Go to your story manager and select "new chapter". NOT repost story. The first thing it asks you is which chapter it is you're uploading. All you have to do is enter the chapter number you want to resubmit.
As far as I know, the system does not work entirely automatically. There will be a human looking at your submission and understand that you want to resubmit a chapter.