Sago palms go through periods where they are actively growing and other times when they are not so active. This is a time when you should be seeing new growth though. Check to make sure the soil is adequately moist and then give the plant a good feeding with a soluble product such as Miracle Gro or Miracid following the label rate. If it is getting decent light intensity it should have the vigor to go ahead and resume some new growth. In deep shade the leaves are often unable to get enough light to sustain good vigor. Also if it is a new plant it may be trying to establish roots and won't be putting new growth on until it has a good root system established.
Thanks for the question. Please stop in again soon!