I have already filed my W2, but I need to file another one, what do I do?

You cannot change the information at this time.  You will need to wait until your return is accepted or rejected (January 23rd, 2017 is when the IRS opens their e-file system).  If your return is rejected, you will be able to modify before you resubmit.  

If your return is accepted, you should amend, or correct, your return if the original entries in the 1098 area were incomplete. There is no additional charge to use Turbo Tax to amend your return, but you will need to mail in the amended forms, as the IRS does not accept e-files on amendments.   

The amend form should be available in mid-February, to make the corrections. This will also allow time for the IRS to receive the original return and make sure there are not any other items that need to be addressed.

More about amending here https://ttlc.intuit.com/replies/3318732