Replaces the selected region with a simple cubic curve . A keyframe is set at the beginning and end of the region, if one does not already exist. A smooth cubic curve joins these two keyframes and replaces all other keyframes in the region.
When you select the Reinterpolate filter in the Filters window, you can set the following parameter:
Resample and Resample Frame Rate
Resamples the selected region by creating keys on the curve (see Resample filter). 
Reinterpolate A. Original curve B. Reinterpolate applied (with Resample)