Currently, OnDemand customers have no ability to control page breaks to create a clean pdf export. This is critical when creating client-facing documentation as often you need to ensure content and tables or content and image are kept together. Or, you want to minimize orphan or widowed content - makes no sense to have a section header at the end of a page and the content start the next.
There are hacks you can do, but they are not supported by Atlassian.
Atlassian recommends using a Page Break user macro; however, OnDemand customers do not have the ability to add user macros nor can they add the HTML macro which would allow them to insert a page break using html.
The easiest option is to provide the Page Break macro out of the box for OnDemand users.