The Southern Astrophysical Research (SOAR) 4.1m telescope, located in Cerro Pachon, Chile, has an active optics system that uses a Shack Hartmann wave front sensor to achieve optimal image correction and focus. This Calibration Wave Front Sensor (CWFS) has two detectors, one to acquire the star and the other to sense the wave front. In 2012 the acquisition camera failed, being replaced temporarily by an SBIG camera. We describe here a project to repair and upgrade the CWFS, extending the lifetime of this critical telescope component. The upgrade includes two new detectors and modifications to the existing software in order to communicate with the new cameras. Also, new mechanical supports were fabricated to mount the new cameras, and a new field flattener was designed for the acquisition camera. A laboratory rig with all the components was setup so to carry out extensive testing before installation on the telescope.