Damn straight you can! Your account with Sportsbet.com.au will not expire, however some of your details (for example credit or debit cards) may well have bitten the dust.
Simply log in to your account, and there you'll be able to update all your personal details via the 'My Account' section, as well any changes to your payment details.
If you are having trouble accessing your old account, don't hesitate to give our Customer Service team a holler.