Assuming you have no bookmarks or such, here is a process that will do the job with a fair amount of sorting after the fact. There are some JavaScripts for this action that others may come by and share with you if they have them. So for the workable, but painful way:
1. Crop all pages for the odd pages and print to a new ODD.PDF.
2. Uncrop (ctrl-Z) and crop all pages for the even page side and print to EVEN.PDF.
3. Open the ODD file and insert pages for the EVEN file.
4. Open the pages option (you can actually narrow the document screen to concentrate on the pages view) and move the even pages to the proper location, one-by-one (a lot of work!).
Not necessarily recommended method, but will get you there. If you can wait, see if one of the folks comes by with a JavaScript. You can also search for a JavaScript to do the job. Good luck.