# in that day

"on judgment day"

# did we not prophesy ... drive out demons ... do many miracles?

"we prophesied ... we drove out demons ... we did many miracles." 

# in your name

Possible meanings are 1) "by your authority" or "by your power" or 2) "because we were doing what you wanted us to do" or 3) "because we asked you for the power to do it"