The Budesliga side, who avoided relegation from the top flight with the help of Ji's five goals, will have to pay £2.5m to secure the South Korean's signature.
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 more than they envisaged to land the 21-year-old.
They are ready to offer £1m.