for sure what helps me to engage is the comments number. that works for me more than any other stat, cause i see there is a discussion i can learn from and eventually engage in.

anyway maybe you could put a little counter on or under every of the buttons that are already there?

like:

  • under or on the right of the reply button, the number of the replies already there
  • under or on the right of the repost button, the number of the repost already made and you can see who did it by clicking on it
    etc etc

That's all folks...