That's right, 8.1 is now totally obsolet. Beter to start from 8.2.1 or if you like to try the latest 8.2.92 but be aware it's a development RR anything can happen.
If you did your installation of 8.1 on one single partition, then it's possible to erase 8.1 and install the latest version on the same partition, you need to chosse Erase then Install at the Main menu in the mini ISO