I do not have a native solution for this; but if you're interested in pushing your file attachments to the cloud; and linking them to Quick Base; Juiced Technologies' products integrate well with Amazon S3 (super cheap for storage); and then you can copy your apps without limitation. Also, they have a tool that will push all your existing file attachments to the cloud. Worth talking to them, I think.
Another solution if your purpose is simply to create a copy of the App; but still need the file attachments is to build a formula that will "access" the original source files from the same record ids; since the file attachments would be stored in the same original record ID#s as would be in your copy. New records however would be stored inside the copied application.
It depends on what you're copy application purpose is as to a good solution.
