better refinance to other bank coz for existing customer for ur own bank the interate revise wont be much different. YES u can top up ur loan based on the current market value for cashing out some own use. but the rate wont be tat attractive enuff.
For ur case i did suggest u go for CIMB Bank. They do provide ZEC wif BLR - 1.8~ BLR-2.05 ( NZEC ) . Can consider that =)

because before year 2007 , all the BLR are PLUS , ending of year 2007 started BLR - 1% , tats y for TS case bought in year 2000 , interest rate definitely more than 7 %