Yes. It's possible to move data from a Wii console to Wii U with a system transfer. This will move across data including Mii characters, purchased content and save data, so you won't lose your progress in your favourite Wii games. However, please note you will need both your original Wii console and your new Wii U console in order to do this, as well as an SD Card and Internet connection. In addition, please be aware you cannot move individual items of data. All Wii data will be moved as a set. Data will be deleted from the Wii console once transferred, and cannot be transferred back from the Wii U console.