The Giants cut ties with Chase Blackburn once, but they are not planning to do so again. There’s a good chance the hard-working middle linebacker will be back for a ninth season, but only if the price is right. “The Giants have expressed a desire to re-sign Chase,’’ Richard Katz, Blackburn’s agent, told The Post Friday. “We believe Chase has been very valuable to the club, both on and off the field. Right now we are assessing his dollar value to the Giants and reviewing all possible alternatives including the Giants.” Blackburn, who will turn 30 on June 10, started 15 games this past season on a defense that allowed a franchise-record 6,134 total yards. The Giants already have parted ways with a starting linebacker this offseason, releasing Michael Boley last week.