is she flying with other birds? What do the other birds do? This is a common hard-to-break habit. Mine always did this until I had tosses them two weeks without a break, reaching only 5 miles (yeah, I baby my birds

).
again, is this the only bird being tossed? single bird tosses are death to a pigeon. Is she very hungry on tosses? If not, she's got no motivation to come back quickly. Feeding less will also help birds get fit.
For longer loft flys, toss to keep them in shape (always fly in groups of 4+) and fly them hungry, but not to hungry where they will drop down at first sight of you with food. Have a food call, so they KNOW if you are feeding them, or cleaning loft, etc. Without a food call, all they see is you around the loft and think FOOD!!! Fly birds early in the day, so they have at least three hours of daylight.
Remember, keep birds healthy and in shape. Toss once a week (at least) clean loft regularly, loft fly regularly, feed as much as they can eat in eight to twelve minutes. I always feed my birds once a day all they can eat in eight minutes. I have been corrected for feeding two little food by fancies. Guess what, there fat birds last ten minutes in the air while mine go two hours! Haha.