I used the ReFile after I added a T5. Spoke to Service Canada and they told me to do it this way. After I added the T5 I went to the Interview tab there is an item on the left called CRA ReFile ( third item in) for electronically resubmitting the federal return. Then follow the process after that go to NETFILE you will see it will say ReFile your return. Press and your file will be sent and a confirmation number will appear.
Go to MY ACCOUNT on the gov't website and check a couple of days later. You will see they have received it.
Hope this helps.