How can I change the "Read More" text for a post preview when using post.preview instead of post.get_preview in Timber?

Before Timber version 1.3.1, if you wanted to change the Read More text for a post preview, you could use {{ post.get_preview(50, 'false', 'Keep Reading') }}. This function has been deprecated and it is recommended to use {{ post.preview }}, but it doesn't seem to have the ability to filter the Read More text easily.