I used to be able to click on the clock bubble and it would open the “OK Google” option. It no longer does that. I’m not sure how to reactivate it. Can you help?

Yes, I miss that option too, but it affects every watch-face, not just Bubble Cloud, because it was taken away by Google in their 5.1.1. update, many people are disappointed because of it:
►https://www.reddit.com/r/AndroidWear/comments/377dpg/511_sucks/crkalx5

Currently, as described in the above discussion, you have to swipe from right to left 2 times after tapping the black clock:
►tap white → turns black
►tap black → list of apps
►swipe left 2 times

There is one workaround the community has found: in the list of apps which appears when you tap the black clock scroll down to “Google” and tap that. The second time you do this it will already be on the top of the list, so it’s only one extra tap away → 3 taps instead of 2:
►tap white → turns black
►tap black → list of apps
►tap Google

I am looking into ways to add a mic bubble for 1 tap access though…