The changes of the refund will depend on how the 1098T was changed. Yes, if the amounts were changed and your return has been already accepted by the IRS you should file an amended return. The IRS will only accept amended returns via mail.
The 1040X form for 2018 isn’t ready. Please, keep checking the following information on how to amend your return; it will be updated once the 2018 form is released:
https://ttlc.intuit.com/replies/3288565