The main reasons for refinancing are:
To take advantage of product features that are not available from your current lender.
To take advantage of a new interest rate or competitive offers with a new lender.
To secure additional funds that may not be available from your current lender.
To release equity to purchase an investment property.
Consolidate debts - such as credit cards, cars, ATO, etc...
Refinancing can knock thousands of dollars off your total mortgage cost and years off the loan term so that you can own your home sooner and for less.