If you have already filed and your tax return was rejected then you can refile. If your return was accepted, then you will need to wait until that return is processed. Once processed, you can amend the original return (it is not refiled).
I was working on my taxes, went to take a break...when I logged back in It said congratulations! You have filed your 2017 taxes!!! I didn't efile! something wrong with turbo tax...now I'm screwed!