Might I suggest killing the "Improved Ki" feats and taking their stuff?

Seriously. Give the monk a "ki progression table" of ki attack/defence abilities known. Limit how many are active at a given time (total level of abilities active?), modest cost to switch up which are active.

A feat could grant more known, or meta ki feats that modify what a ki ability does (if flaming fists is a level 1 ki attack for +1d6 damage, enhanced flaming fists is +3d6 as a level 2 ki attack).

What is more fantasy monk-like than a character that can set their hands on fire?