I’ve found that the best way to get out of a creative rut is by trying something that you can’t fail at. I don’t mean that there’s no way to fail, because I’m sure there is, what I mean is to try something without the pressure to succeed. No clients, no deadlines, just you and your camera (or whatever your instrument of creativity is). 
This is what it looked like for me: I took my husband out of the house (he vowed to be my photography subject for life the minute he said “I do”) and I shot multiple exposures of him. There’s no way to fail at it! The results were better than I expected; then again, I didn’t come with expectations. It gave me a renewed sense of purpose in what I was shooting, while practicing some lighting techniques I rarely use (I tend to shoot early in the morning or early evenings, never in noonday sun). This exercise reminded me of what play time looked like when I was young: I was free. And just like that, my creative rut disappeared.