Ooh, getting that gait back could be difficult. Do you know what kind of gait she did? My Kentucky Mountain Saddle Horse does a single foot or ample, but there are many different kinds of gait. Have you ridden gaited before? One thing I've heard recommended to help strengthen gaiting muscles is to ride uphill. For some reason it makes it easier for them to gait, and they have to build those muscles to maintain a gait for any amount of time. And not a steep hill, a more gently sloping hill.