Sadly, Apple claims that its installer and upgraders are SUPPOSED to also update the Recovery Partition whenever the partition associated with it is updated. In my experience, it is hit and miss. This is true whether upgrading from a major release to another major release (El Cap to Sierra) or point release update (10.11.2 to 10.11.3 for example).
You are more likely, but not guaranteed, to have the recovery partition updated during point release updates if you use the Combo update versus the incremental updates (i.e. from 10.12.1 to 10.12.2). Also if you have multiple macOS boot partitions on the same drive, seems to confuse the update programs as well.
Carbon Copy Cloner, if you already have that, will also create a recovery partition if missing. In my experience, I almost never do a major release upgrade over an old one, I always do a fresh install. I realize that isn’t always feasible for some people, but it’s the method most liklely to cause the fewest problems of any kind, in many other areas, not just recovery partitions.