Pay off mortgage or refi to buy more property

[Jules H]

I have a rental property on a 15 yr mortgage with only 5 yrs left. Should I refi and take money out to buy another property or pay off the mortgage as soon as possible. Rate is 5.25%, mortgage is $1800 pm, it rents for $2500 pm. We are in our 40's, live in CA and have 4 rental properties. I'm torn between piece of mind having a house paid off, and the advantages of buying another property while the market is down.