Hi,
The good news is that upgrading mojoPortal doesn't usually break things with skins.
You can check out the "Upgrading Skins" doc for notes on what might need to be updated in your skin.
If you need or want some help with upgrading and making sure your skin gets upgraded as well, submit a ticket and we'll help you out. It should only take about an hour once we get started.
Thanks,
Joe