Depends on want you want to do?
Often just smoothing can do a lot. Start smooth and release “shift” directly after you began will swap into a different smoothing mode.
If you want turn your sculptris mesh into a “serious” zBrush mesh, I tried yesterday a pretty satisfying way.
Thanks nebular for this nice tutorial!
GoZ to zBrush.
Duplicate your mesh.
Take the duplicated mesh and follow this tutorial:
http://www.zbrushcentral.com/showthread.php?173177-Tutorial-on-creating-low-poly-mesh-with-qRemesher-from-high-ress-DynaMesh-model&p=984487&viewfull=1#post984487
After you have finished, you can subdivide and reproject again.
Heavy faceted, low density areas of the original model will be reprojected also.
But those can be smoothed out after with easy. It’s quad mesh now 
It’s not such a long way to got but ends in a pretty nice&flexible mesh almost without loosing detail.
HAVE FUN