Are you using one of our App SDK's?
http://developer.help.rallydev.com/app-sdk
In 1.x RallyDataSource.findAll will automatically page for you and return all results. There are good examples of how to use it here.
In 2.0 preview the WsapiDataStore has a limit parameter you can set to Infinity or some other large maximum number of results to return.
Examples: http://developer.help.rallydev.com/apps/2.0p5/doc/#!/guide/appsdk_20_data_stores