Hey, it wasn't a particularly good cloak even without Kirk's sniffer torp - the ship became visible every time it fired a torpedo!
You don't need better sensors against that sort of thing. You need faster targeting systems, so that you can fire on the ship during the short time it is visible. We don't know whether TNG systems are faster than TOS ones; Kirk never had to put up with an enemy as swift as the EP-607 drone from "Arsenal of Freedom", the only known case where the targeting systems of the E-D could not cope. But this just means we can make that assumption if we wish.
Every Klingon skipper in TNG/DS9 seems to agree that they can only get off one shot after decloaking before the enemy responds and blows them out of the sky. There isn't time to recloak. Chang's ship, which decloaks its bow for firing for a second or so and the recloaks, could be toast by the same token.
Timo Saloniemi