Ask your CEO (or her assistant) if she wouldn’t mind sending out a few personal emails to top community members as thanks for everything they’ve done for the community this year.
They have to be personalised (no mass cut & paste to the entire community) and they have to come from the CEO’s account.
You can even draft them up. Be sincere and honest. Don’t pretend the CEO is reading every post when they’re clearly not. For example:
I’m the CEO of [company] and my team have been telling me about your great contributions to the community over the past year. They especially liked your posts about [x], [y], and [z].
I just wanted to drop you a quick note of thanks.
Our community only works because of key members like you who take the time to help other members. Please don’t ever hesitate to drop me a line if there is ever anything I can do to help.
CEO, [company name].
If you can’t get the CEO to send out a few pre-written emails from her account, then find the next senior person who will.