No, you can't correct your extension unless it is rejected for e-file. While it is pending, you can't do anything. If it gets rejected, you will get a chance to change your extension and re-submit it.
If it is accepted, you can't change it, but the IRS doesn't waste time trying to enforce extension requests. If you entered too high a payment amount, just pay the actual amount that you estimated you should pay.
If you set up an automatic debit to pay your payment and it's the wrong amount, you can contact the IRS and get the payment changed. Follow this link and use the information under Cancellations, errors and questions to change the payments you set up.