While there isn't a built-in feature that can export RP projects as XML files, you can try doing this by using the Axure RP API and a bit of coding. You can download the API from our website here:
Axure RP API
The download link there includes a sample XML Generation Project written in C#. Please note that it is generally recommended that you have some experience working with C# or writing code before getting into the API. If you have access to a dev team, they may be able to help you here as well.