If you pass a course by taking the regular exam you are not allowed take the resit (kontinuerings) exam in the same academic year. But you are allowed to take the regular exam again the year after.
The best grade stands.
If the course grade is set based on multiple evaluated assignments (mappeevaluaring) then all assignments must be redone.
More details https://innsida.ntnu.no/wiki/-/wiki/English/Retaking+a+passed+exam