Interesting. I never noticed before that Jesus uses the same example of working on the Sabbath in both Luke 14:1-6 and Luke 13:10-17. It also intrigues me that in ch. 13, Jesus waits for the synagogue ruler to express indignation. Here in 14, Jesus addresses the non-vocalized accusations.
For something much more profound about this miracle, check out what I wrote two years ago. Combine that with what I write above, and the repetition highlights how serious Jesus is about calling them to repentance and faith.