It looks like you're just assigning a specific, named animation when the button is pressed. Depending on your needs, you could store your various animation names in an array and present them from there.
You could store your current array index in a variable and each time you press the button, you could increment your array index variable and load the animation stored at that index. Once the last animation is loaded, another button press could load the first one again.
You could easily expand on that by providing 2 buttons, one to move forward through the animation array and one to move backwards.