I have a pattern completed, but now want to resize it. Whatever I'm doing only resizes the layout and not the design. Any ideas on how to resize the design? Do I need to print it out and scan it back in?
I'm not sure what you mean by "resize". If you mean adjusting the actual stitch count, the ONLY way to do that is to redo the pattern.
If you mean resize the resulting pattern with the given stitches, that is done by doing it in a smaller size stitch, such as 18 count instead of 14 count. That does not require any changes to the pattern. The fabric count listed is just a "suggestion" and the same pattern can be done with any count fabric.
For example, have a pattern that is 45x45 and I want to make it 25x25. What would be the easiest way to accomplish that? I'm also trying to use it towards a latch hook design, so slightly different medium but the design is still the same (as in 1 stitch or yarn per square).
If you are actually talking about reducing the number of stitches, that's a total re-design of the pattern or a crop of the pattern (just cut out the outer stitches). If the former, you have to start over again.
Using the same pattern for latch hook is fine. Any craft that can be defined as a grid can be expressed by PCStitch.