The same thing has been happening to the Canadian dollar, after I'd made some expensive commitments to travel in the US.
Whatever you actually owe on these loans needs to be paid, regardless.
Beyond that, you have more choices. There is no saying that the US $ has stopped going up, so this may be the cheapest price you have for some time. The Cdn $ has gone from 88 cents to 78 cents in recent months, but I've also travelled to the US when it was 65 cents. Do some research on what legitimate forecasters say is likely over the next year.
On the other hand, if you don't know what the US dollar is going to do, you could do some dollar cost averaging, and make payments over the year you are in Aus. (You will be adding interest costs by doing that, though.) If the US $ continues to go up, you've lost some money, but not as much as if you waited until you were out of Aus.
The optional part could wait, but you'll incur interest. If you go to Europe, the exchange situation won't be better.
Do the math for different scenarios.
It sucks, but some decisions work out and some only work out partly. Don't let it take the joy out of the year.