If one hand is weaker than the other then a good, well known way of strengthening it is to take advantage of the keyboard's mirror symmetry about D and Ab. Take any figure, whatever you are working on, whatever is troublesome and exercise it with each hand in positions reflected about D and Ab. Try, without strain, to make the movements and sensations identical to those in the stronger hand. It is a purely physical trick as much inverted music might not sound any good, which is why I have used it mostly on my silent Virgil Practice Clavier. However, it does work if you persist with it and if you are an improviser it is also a path into new keyboard vocabulary.