A;so, if you aren't giving her some hay, might be good idea to do it? That will get her mind off it more than likely.
But more miles is best thing.
Too, make sure your driving is safe, and not going into turns or stopping too fast, and also that trailer is level.
Always amazes me the people that never think to check that, as I've literally seen a trailer at such an angle the horses were all the way against the trailer door, and that was only thing keeping them in trailer.
Horses make me a better person.