How to get a horse to lope better?

My Arabian she doesn't lope to good. I can get her to slow down enough for the lope but then she will go into a trot and I will kiss to get her to speed back up a bit and she will go right back in to a fast lope. Then I will try and get her to slow down again she will lope for a few feet then to a fast trot. Is there anyway I can get her to keep loping with out dropping to a trot and then going back to a fast lope?