I got an error when command "gcloud preview app deploy app.yaml --promote" :
ERROR: (gcloud.preview.app.deploy) Error Response: [13] CPU Quota Exceeded: in use: 7, requested: 2, limit: 8 Version: 20151201t142343.388948918338383472
Is there anything to solve this situation?

Since I just ran into this too, and was a bit boggled:
it seems like every deploy you do for e.g. a node.js project creates a new compute engine CPU. If you go into your project's gcloud dashboard, you can see the number of compute engine instances - remove old ones, and you can deploy again.