When you need to create a repeating pattern in Photoshop, the usual process is to build your repeat tile and then flatten the image so you can apply an Offset filter to see how your tile looks when repeated. However, if you flatten the image, you can't fix anything if you dislike the results. One way to work is to create a "merged copy" layer. You can do this by positioning yourself on the top layer of your image and pressing the COMMAND + OPTION + SHIFT +E keys on the Mac or the CTRL + ALT +SHIFT +E keys on Windows. That is the "have the cake and keep it too" technique that has been part of Photoshop for a long time. It creates a layer at the top of the image that contains the merged content in all of your layers. You can then apply the Offset filter to just that layer and if you hate the resulting repeat, you can simply trash that layer--only--and rearrange your original layers.
A better technique is to use the Smart Object feature that was first added to Photoshop in CS2. I call this the "Jack-in-the-Box" technique because it allows you total flexibility to keep your layers, scale and rotate them, and filter them. Nothing is ever damaged and you can recover or revert at any point.
So, take a look at this video and see what you think!
--Sherry aka the prancingpixel