Don't waste the beef broth. Corned beef just needs to be cooked in plain water with the seasoning packet provided.
I simmered my corned beef brisket on top of the stove for about 2 1/2 hours yesterday. Then I took it out and put lots of cabbage wedges, potatoes and carrots in the dutch oven and put the brisket back on top with some of the original liquid. Then into the oven for 2 hours. It was absolutely delicious.
Enjoy your corned beef sandwiches!