Keeping Image Galleries after changing themes

Hi

I just bought a new photo-based theme to replace my old photo-based theme and I’m not able to keep the dozen galleries containing about 300 images intact in the new theme.

I tried to use the export xml files but that does nothing, also tried Next Gen Gallery and nada. When I edit my existing pages that contain(ed) my galleries I get ALL the images (300+) displayed on one page.

I searched the forms and haven’t found this issue which is surprising as I can’t be the only person who has created lots of image galleries in WP and then changed their theme. Must be a better way to manage/control these things.

The theme’s designer simply suggests uploading all the files again as if I have a couple of weeks to re-do all that work, let alone re-creating all those pages which already have content and permalinks set up.

Thanks for any help or advice!