Ni-based superalloys that are difficult to deform are highly susceptible to cracking during additive manufacturing. Despite their importance, limited research has been conducted on the additive manufacturing of GH4975 superalloy. To address the cracking issues associated with such superalloys, this study focuses on additively manufactured GH4975 superalloy to investigates various crack repair strategies. Experimental approaches, including the addition of TiC heterogeneous nucleating agents to the powder, hot isostatic pressing (HIP), and hot compression, were used to explore effective methods and underlying mechanisms for crack healing. The results show that the calculated mismatch of close-packed planes between TiC and the matrix is 6.0%, with an atomic mismatch of 0.4% in the close-packed direction. Following the addition of nano-TiC particles, the average grain diameter of the GH4975 superalloy decreased from 41.9 μm to 27.2 μm, indicating significant grain refinement; however, the cracks were not effectively eliminated. The HIP repair method further removed some cracks, but microcracks wider than 3 μm remained unhealed. The most effective crack elimination was achieved through hot compression at 1200 °C with a strain rate of 0.1 s^-1 and 30% deformation, which nearly eliminated cracks at the center of the as-printed sample. However, the crack healing ability decreased when hot compression was applied to samples that had already undergone HIP treatment. The main mechanisms of crack healing were identified as matrix plastic flow under external pressure and the diffusion-driven crack filling by Al elements.