Thanks Michael,
the message appears when the package "Rotations`OrientationalSampling`" is loaded and added to $Path. When Needs[..] is executed again, Mathematica looks to see if the package is already on $Path (and therefore loaded), and does not load again if it is there. So there is no way to force Needs[..] to regenerate the message a second time, without redefining the built-in Needs function, which might have unintended consequences, and is inadvisable. So there is no straight workaround for this.
However, as you discovered, executing or Orientations[] or OrientationsAndWeights[] will list the available orientational sampling schemes.