As Mike pointed out, you can add additional Lightroom edits on your Photoshop file once it's saved and brought back into Lightroom. I'll do that often, but usually limited to things like cropping, post crop vignettes, and sometimes split toning.
If your asking about how to take the original lightroom RAW file and re-do some of the develop settings, then bring that back into the Photoshop file, that's a little more difficult. There's not really a direct way to do it automatically.
However, if you have a good non-destructive workflow in Photoshop and save your layered file with all the adjustment layers, then it is possible to re-develop your image, edit it in photoshop, and copy/paste it into your existing layered file on top of the background layer. Obviously you'd lose things like dust spotting and true pixel edits, but for some files it would work. I've done it before when I wanted to make a basic exposure/white balance adjustment on the RAW file, but I was well into the editing process.