How to obtain a bigger size projection?

[Jaffa]

I've stuffed up.  I want to end up with an image of 2160 pixels in depth (2547 in width) - however I currently have an image sized 993 pixels deep (2567 wide) at 240dpi.  This happened because I was playing around with a base image that I had sized for the internet.  Meant to stop at an early stage and restart, but forgot and now I have processed the image to just as I, and others, like.   The image is to be projected and is not for print.

Now it is easy to go in and resize, but then am sure I would get pixelation, or at least, less definition.  What should I do, I have all the layers, so I know mostly how I arrived at the final image.  Could I somehow transfer all layers except the background layer to a new background image the size I want?

[firstdefence]

You should be able to either copy and paste those layers to a new document, be aware you might have scaling problems with certain layers when copying and pasting and without know what layers you have its hard to say what the effects of copy/paste would be. You can save things like adjustments as presets for use at a later date.