A green body with a density as high as possible is critical to diminish the crisis of deformation or cracking when large-size parts are sintered. Here, a new method, i.e., re-fluidising the aged ceramic gel is developed to prepare the high-density green body. Alumina slurry with 56 vol% solid loading and copolymers of isobutylene and maleic anhydride were aged without vaporisation and re-fluidised by non-intrusive shearing after removing the exuded water. The re-fluidised slurry was re-casted. The resultant wet gel was dried and deboned at a low temperature. The relative density of the obtained green body was 64.6%, 1.5% higher than that without aging and re-fluidising. The linear sintering shrinkage of the body decreased by 0.7%. The enhanced green density is explained from the viewpoint of the solid loading and the structure of the slurry.