Even though Mint does not officially support dynamic online upgrades, you have nothing to lose by trying. The worst that can happen is that you have to nuke and reinstall.
Just be sure to back up everything just as if you were going to install fresh.
Here's a tutorial: http://community.linuxmint.com/tutorial/view/62
When I upgraded, I nuked and reinstalled, but my /home is on a separate partition, so all my data was still present and, as I reinstalled the applications I use, the application settings were already present.