In TurboTax Online, you can prepare and e-file one federal and up to five associated state returns under the same login. For more information, please see the following TurboTax FAQ: How many times can I e-file using TurboTax Online?
However, if what you mean is that you have received additional tax documents that you need to add to your return, if your return is rejected, you can go back into the return and make the needed changes.
If it is accepted and therefore needs to be amended, here's how you can do so: How to amend (change or correct) a return you already filed