Gitlab-runner not pulling latest container version

On our GitLab instance I had a CI job fail and it was basically due to the problem in the container that the build was runner in so I fixed this in the container and pushed a new version up to Docker Hub. However when my pipeline runs it’s still running in the old container version that had the problem. I’ve tried clearing all containers from the gitlab-runner host with:

docker system prune -a

and then trying my pipeline again but it still runs in the previous version of the container and therefore fails. How can I tell GitLab to pull the latest container version?