It’s time to prune your fruit trees and many people don’t have a clue on how to prune correctly. Though there are different pruning techniques for all plants most fruit trees are about the same. This description does not go for grapes or blueberries, by the way. That’s a whole other science.
It’s actually pretty simple. Cut branches cleanly at a joint. Cut anything (suckers not main branches) that is growing upward, anything that is crossing another branch and anything pointing inward. Look at the tree and imagine it with leaves and then make sure there will be good air circulation and that there won’t be clusters that shadow other spots. Use tree spikes every four feet around the drip line unless you are trying for an organic crop.
Now to reclaim an old tree that stopped producing you have to take time and lots of it. Each year cut off a major branch and promote new growth. Use tree spikes around the drip line. Maybe get some mason bees. Pay attention to what the tree does. Does it get healthier or weaker from this action? If the tree still doesn’t produce after a couple years you may consider replacing it.
It is pretty important to prune if you want fruit. Trees that are not pruned often alternate years of production. One year pretty good and the next year little or nothing. Prune to balance the tree as well. You don't want the tree to burden all the weight on one side or you may find it uprooted one day.
Never ever, ever top a tree. That will always end in disaster. Topping, believe it or not messes up the trees roots and the open stumps in the crown to become diseased and rotten.