In Corinthians it says prophecies shall cease.
That has to do with the gift of prophecy, not propecies already given.
I know Preterists believe that all prophecies have happened.
"Preterist" is not a denomination, and your assertion is incorrect.
Some preterists believe all the prophecies have been fulfilled; these are called "hyper-preterists". Generally, most preterists believe that
many prophecies have been fulfilled, but not all.
What is the name for the denomination that believes prophecies are ongoing?
The term for people who think that significant end-time prophecies have yet to be fulfilled is
futurist, but again, that's not a denomination.
There is no relationship between 1 Corinthians 13:8 and the various views regarding fulfilled prophecy. ALL God-given prophecy will be fulfilled if (A) it has not been fulfilled already and (B) the conditions for its annulment are not met. God's prophecies don't simply "cease".