I had these exact same feelings not too long ago -- not necessarily writing the same exact style as you, but I had my formula and it just always came out that way and I started to get tired of it. What helped me was basically putting the guitar down for a while (I ended up not playing for about 7 months, although it's not like you have to stop playing guitar completely or for that long), and focusing my efforts on the piano/keyboard. I don't know if you play other instruments or if you have any desire to, but what I did was used the piano to write in another style that is close to me which is video game influenced soundtrack material.
By the time I picked up the guitar again, the material I started to write had more depth. However I also did put forth a conscious effort to write using different progressions/styles than I normally did. Later it started to come natural, but I needed that initial forceful push to get me out of my rut.
Don't know if that means anything to you, but from your last couple of posts I felt a sense of relatability.