Yes, you can still make changes to the return after paying for your TurboTax fees up until the point you actually file the return with the IRS/State during the e-file process steps.  

(I am assuming you are referring to TurboTax fees and not the IRS payment.  If you made a payment to the IRS, but haven't actually filed the return, you could still make changes but it's possible that any changes you make might change the amount you owe the IRS.)