You do not NEED to, but I would recommend it. Are they cotter-pin cranks? If so it might be a challenge to remove them. Check sheldonbrown.com for how this is done. If you do get new cranks, you will also need to swap the BB and make sure it is appropriate in terms of compatibility with your cranks/a good chainline (and the threading of your BB shell, which should be English). You do not need track-specific cranks, but just make sure whatever you use can be set up properly. Again, consult Sheldon (RIP), he is your god now.