I was reading a post from a priest concerned that his homily for the 4th Sunday of Advent was exploring similar themes from 3 years ago.
I do not think priests need to worry about retreading homilies.
First off, if most people are like me, five minutes after we hear a homily we have forgotten it. Priests have the charism of forgetting what people said in the confessional and the laity can do the same with homilies – even a well-crafted one.
Secondly, those in the pew are much like a river where you can never step into the same place. Often something that passes you by one day strikes you on another.
“If you look at a thing 999 times, you are perfectly safe; if you look at it for the 1000th time, you are in danger of seeing it for the first time.” G.K. Chesterton (The Napoleon of Notting Hill)
As to my first point, even if made in jest, there is a reality to it. Still not being able to recall the details of a homily is not the same as not hearing it. I have often been frustrated in reading books and finding that so many of the details have now escaped me. At least this was true until I realized that this was not the same thing as this being a waste of time. There is much that we internalize and process that we are unaware of. We are not made of the stuff of constant epiphanies. It takes time and reprocessing what we know into how we live.
Now as to bad homilies, by all means, retire those.