If you have Home Brew Channel, it is soft modded. Go through Softmod Any Wii guide to get your system current and be sure to include the files for Shop Channel v21 in Chapter 2 when you get that far.
If you don't, then it probably is hard modded. I can't speak for if an update will break it or not as I have no experience with hardmods, but you can still softmod your system on top of the hardmod using the same guide I mentioned above.
A link to the guide is in my signature.