You can find the information via the transport Canada website; however, basically your Canadian IR exams need to be rewritten after more than 2 years of not having kept up your Canadian IR. You can avoid having to redo the written exams by submitting copies of your current foreign IR (ICAO licence). When you do return to Canada all you would then need to do is an IR ride. Applying for a foreign type rating to be added to your Canadian licence is very easy (and cheap), just download the form and it tells you what you need to submit. This info may not be 100% accurate BUT it is very close if not completely correct (at least it was as of the last time I did it recently).
