Complex sentence: When the project was finally reviewed again for the modernization of the People's Liberation Army Air Force, it was already too late and outdated, instead, China developed phased array radar for its KJ-2000 AWACS.
Split into simpler sentences: When the project was finally reviewed again for the modernisation of the People's Liberation Army Air Force it was considered obsolete. In the KJ-1's place PRC developed a phased-array radar for its KJ-2000 AWACS.