Where exactly did it crack? If it's towards the middle of the brace, you can cut a strip of acrylic and glue it to the brace. If it's closer to the front or back it will need to be replaced.
I've also seen where people cut their cross brace out and replace it with a piece of acrylic and then use nylon nuts and bolts to secure it to the trim.
sells replacement trim. You can try calling them so see if what they have will work.