if you just need to export, export your document to pdf and then convert the pdf to jpg...
if you want to recreate the file, you can try to first rescale all items, by group everyting and resizing with the keys alt (resize) and ctrl (keep proportions) pressed.
and then copy paste everything in the new file (or first copy paste and then rescale... check what works better for you).
if you can use the snapping to guides and margins you might get to a good result...
depending on the specific content it will work more or less well...
for the fun:
- in scribus 1.5 i can get down to 1%... and my crazy monitor (a laptop 13'...) can show the whole width on 2/3 of the width even at 10% : - ) ... so you might want to get a monitor with a few more pixels... or scribus 1.5 if you're comfortable with working with a development version for scribus