There's no way to just copy the settings from one gallery page to another but there are a couple of things that might make life a little easier.
(1) If you already have a gallery whose settings are exactly as you'd like them to be, then you can clone the gallery using Showkase's 'Site -> Import' functionality, essentially importing an existing Showkase page to create a new Showkase page (within the same site).
On the 'Site -> Import' tab, just enter the path from your web root directory to your Showkase site's directory (starting with a '/'), click the 'Scan' button, select the gallery page you'd like to clone and click 'Import'.
Once your new gallery page has been created by the import process, it will be be identical to the original gallery page and you can then just change the images (deleting existing images on the gallery page's 'Images' tab and uploading new images on the gallery page's 'Upload' tab) and any other settings such as the page title.
(2) If you have a particular set of configuration options that you'd like to use for all galleries throughout your site, then you might like to set them in 'Site -> Customize Viewers -> Edit (Juicebox-Pro v1.5.1)'. Configuration options set here will be used as defaults each time you create a new gallery page and will prevent you from having to set them individually in each separate gallery page.
I hope this helps.