All aspects of your workouts are subject to monotony — even stretches. So if you've found yourself losing inspiration, it might be time to switch things up. But you don't have to reinvent the wheel for each stretch. Sometimes all you have to do is change your position.
For example, you can change a stretch from standing to lying down. Another simple swap is to change a two-limb stretch to a single-limb stretch, focusing on one side of the body at a time. If you decide to try something new, just remember to go slowly and stop if something feels uncomfortable. Stretching should help you avoid injury, not cause it.