Hi mate,
I dont know wether or not you need to take the TRA form with you when you go, but I do know that you can get a replacement. I applied and got my TRA back in 2000, lost it and applied for another copy recently when my family and I decided we definately want to go.
They do stress that if you lose it again, it will be a problem, any way, try this address..
traenquiries@dewr.gov.au
Good luck mate!