Hi I am an NXT user myself. they are coming around on usability but still have a ways to go. If you have your nxr account number and password you can access it off of any system. so 1sr weite down your accnt number just in case and the update. don't be alarmed if it says you have a zero balance it will often do that till the block chain catches up. good luck! oh yes and depending on how long ago it was since you bought the NXT you will likey have matching Ardor tokens in the asset account.
I will try this and let you know soon.