The South Korean hitman moved to Germany on loan in the January transfer window.
Despite being used in central midfield or out wide, Ji netted five goals in 17 appearances, including the third in Saturday’s 3-1 final day victory over Greuther Furth, which clinched Augsburg’s survival in the top flight.
A clause was inserted into the loan deal to make it permanent when Ji first joined Augsburg, but the cash-strapped club will have to shell out £2.5m to activate it.