Have you got your old IR notes? I would suggest re-learning them and practising on RANTXL, as I've always found Flightsim rubbish for IR flying. Having said that, some of the add-ons are good quality and might be worth considering.
In addition, I would have thought a sim session with an IR instructor before the actual test might be worth considering.
I've not had to revalidate mine yet, so others may have much better advice.
And best of luck!
