Once your IR has gone past its expiry date, you can no longer renew it in an FNPT2 - it has to be done in an aircraft.
If both the MEP and the IR expired over a year ago, you will need some training - how much will depend upon how rusty you have got!
I would do some training in an FNPT2, followed by a session in the aircraft and then the test. You are probably talking about over £1,000.
Linda Mollison