Norfolk pines have distinctively flat branches and short soft needles. They enjoy humid environments. With age, and lack of humidity, the needles along the trunk will fall off. Dead, lower branches, are a sign that the plant has been dehydrated. The dry needles will not come back. These plants do best with consistency stay on a watering schedule. Over watering results in sporadic bright yellow needle clusters that come off very easily, and don't come back. Check to see if the plant is standing in lots of water.
They grow upward, their trunk thickens and the pine bows increase in size. It is not recommended to cut their growing tips off. Its symmetrical shape would be destroyed. The only maintenance pruning to be done is removal of dead lower branches.