Whenever I take a photo I seem to so it exactly the same: small depth of field, very close up, from an angle.

As Jeff Daniels' says in The Newsroom, the first step in solving a problem is recognizing that there is one. You've already taken that step. I like the photos you posted a lot, but I can also see why you might feel like your photography is stagnating. There's a fine line between finding your style and becoming repetitive.

So, you've already identified the things that you usually do, and you've decided that you want to break out of your usual mold. All that's left is to go out and do something different. If you usually go for shallow depth of field, look instead for shots where you can keep both foreground and background objects sharp. If you usually shoot close up and at an angle, consciously decide to shoot from a greater distance and straight on. If you usually like lots of color, start looking at form instead and maybe set your camera to black and white. If you usually shoot low, stand on a chair or step stool for a while.

Beyond just doing the opposite of what you're comfortable with, pick some aspect of photography that you haven't explored much and focus (so to speak) on that for a while. For example, you could stick with your usual M.O., but start shooting long exposure images for a while. Or motion-stopping short exposures. Play with flash photography.

Another path: pick something that you already do, but push it to a whole new (for you) level. For example, you've got the narrow depth of field thing down, so get a set of extension tubes and try macro photography. Shooting macro will let you get razor-thin depth of field when you want it, but it might also make think about when you want to get more DOF.

Plan and execute a project. Instead of just finding interesting details, choose a subject and draw a sketch of a photo you'd like to take, including notes about angle, DOF, colors, etc. Then set out to realize that photo. Once you feel like you've got it, do it again in a different way.

These are all suggestions to help you shake things up, but I can't tell you what your next step should be. You're the only one who can really come up with an answer that's right for you. Just keep pushing your own personal envelope.