Pruning before it begins to leaf out in the spring would be a good idea. If you still have 3ft. of snow, sounds like you have a little cold time yet.
You can usually tell if a branch is dead by scraping a tiny bit of the bark back with your thumbnail. If there is green under the bark, the branch is still alive. Also, of course dead branches are usualy very brittle and some might have broken on their own from all that snow!
Did you mean that the tree is 15 years old, or that's just how long you've been aware of it? If it could be a lot older than that it might be more worthwhile to take it out and start a new tree.
You might also invest in a bag of fertilizer - look for one that says it's for fruit trees. After you prune, when you start to see leaves budding, sprinkle fertilizer lightly around on the soil under the spread of the branches. Be sure to spread the fert out at least as far as the branches reach, not just in by the trunk. Most fruit trees have feeder roots that extend beyond the tree's canopy. The more healthy leaves that tree can make, the sweeter the fruit can be. Leaves make the sugar for the fruit, right? Enough water while the fruit is sizing up is also important.
