Refinance
Whether you are an investor or Owner Occupier eventually your loan and interest rate will get stale. Your lender will stop giving you interest rate decreases. This means that after a few years you will be paying more on your home loan than you would if you moved to a new lender.
I recommend that every person with a home loan have their loan assessed by a broker regularly to ensure you are getting market leading interest rates. By moving to another lender with a better interest rate you will ensure your loan is working at peak performance and that you keep more cash in your back pocket and not the banks.