Once Motorola releases new software, they generally do not off the older versions. My MOL account is only displaying R13.00.01 for Astro 25 Portable, part number: RVN4181AG, RVN4186AF. Looks like they updated it on 28 Aug 2009.
Click the "Resource Center" tab at the top of your MOL page, then select "Software" on the left of the page. Once that opens, select "Two-Way" and then all of your software subscriptions will be displayed.