Steps for using an insert to restore sagging sofa cushions are provided. Over time, the cushion develops a depression on a sitting surface of a deformable member and an elevation on a base surface of the deformable member. The cushion also suffers from reduced elasticity in the deformable member. Positioning the insert between a cushion casing and deformable member of the cushion allows for sagging areas of the cushion to be fixed. The cushion restoring insert thus addresses both aforementioned issues. An elongated elastic member with similar elasticity to the original cushion provides a like-new level of elasticity for the cushion. The cushion restoring insert also increases volume within the cushion casing, causing tension in combination with the cushion casing. This tension counteracts the depression and elevation, helping to return the cushion to a like new state.