I'm not sure what to are trying to do with getCenter() in that case...if i understand you correctly, what you want is, that the sprite faces right when moving to the right and left when moving to the left? If so, the PolygonManager makes this very easy. The texture coords for such a quad/plane are for example (i'm not sure about the actual mapping without looking at it, but the principle stays the same):
(0,0) for the upper left corner,
(1,0) for the upper right,
(0,1) for the lower left and
(1,1) for the lower right
All you have to do now is to assign new coordinates for each polygon by using the methods in the PolygonManager, i.e. to do a flip, just do:
(1,0) for the upper left corner,
(0,0) for the upper right,
(1,1) for the lower left and
(0,1) for the lower right
and you are done. As said, i'm not sure if the upper left corner is really at (0,0) like in this example. Could very well be (1,1) instead, but that doesn't really matter and you can use a little bit of try and error to find out (or use the getTextureUV()-call, that you've mentioned).