My career is in banking, and I know a little about home lending etc... As you built your home last year, I would guess that you're going to be locked into that contract for another 3 or so years, so even if you do find a better deal in a years time you're still likely to pay deferred establishment fees (def), early repayment adjustment (era) (if your loan is fixed) and forfeiting the amount paid in lenders mortgage insurance (lmi). If you kick up a stink you may get a partial waiver on the def and/or era if you're lucky, but it is almost impossible these days to get any form of refund on lmi - it's written very specifically and cleverly into the terms and conditions for both the loan and the lmi.

Kaytee and Pandora had exactly the right idea of a supplementary loan, you could even possibly get the supp loan as a line of credit (loc) if you were super keen, but locs can be dangerous if you're not disciplined. If you get a normal supp loan you can get it over a much shorter term, which means much less interest and you can pay it off faster than the 30 (or whatever) years of your mortgage. It means you pay mortgage interest rates, and can treat it as a small personal loan.

Also, if your bank has the product, I'd recommend looking into whether you can have an offset account as your everyday account and linked to your actual mortgage. Even if you don't have heaps of cash in there, every little bit counts and will save you guys interest and effectively shorten your loan term. It's worth looking into that even if you guys decide not to borrow anymore right now. Most banks can do a product transfer on an existing account to change it to an offset account, keeping the same account numbers, which means no changing direct debits or salary payments, yay