I don't know if she's necessarily getting bored so much as getting frustrated and shutting down and giving up.  My dog does this when he's not understanding a new trick. . . What treats are you using?  She might not want them badly enough.  I recommend using people food--cheese (American or string), hot dogs, chicken, lunch meat.  Dogs like them the best.  She'll want to stay with you because she really wants the treat.  Also, keep her attention by acting like you're really excited and into it.  If you're sounding bored, she will be bored, too.  Try to make it as fun as possible.  . . Just keep at it..make training sessions short and sweet.