1) Allow Chrono Boost to be cast on UNITS and CANNONS to half their cooldown for 20 seconds.
2) In team games, allow Chrono Boost to be cast on allied units and structures to have the same effects as it does to your own units and structures.
A Chrono Boosted hatchery would produce Larva every 7.5 seconds instead of every 15, for example.
A Chrono boosted Bunker would have marines that shoot twice as fast.
3) If that is too good, you could allow an alternate, more expensive version of the spell for casting on UNITS and Cannons, like 50 energy per cast when targeting units or cannons, instead of 25, for example.
This would actually put Protoss' economy booster on par with Zerg and Terran throughout the game.