I have only seen it used in chapter 13. It's probably not in the glossary. I would agree with both meanings you suggested.
However, unless other folk correct me, I think the phrase "planned enhancement" could fit a wider range, and should probably be interpreted in the context that it's used.
For example, in a response to the thread "Ch 6", I used "future planned enhancement" to mean that the mutuals profit for the period is assumed to be "ring-fenced" for the purpose of augmenting future policyholder benefits, and in essence requires reserves to be held to the tune that zeroises the profit now (hence no taxable profits).