You should sell the property. Look, the value of the property is $520k and you owe $100k, so you could clear $420k (minus real estate transaction fees). For our purposes, let's say that is $380k. If you were to invest in stocks with 5% dividend rates, you would clear almost $20k per year. Right now, your monthly income is $1150 per month or $13,800 per year. And stocks go up faster than real estate, historically.
Quite simply, too, condos are not good investments. You would be better off buying a multi-family. Also, you are in California and you just cannot make the same return there on real estate rentals as you can in, say, the Heartland.
Personally, I would sell the condo and use the money you get as an investment. I would not want to do a cash out refi on the condo simply because I do not think it is a worthwhile underlying investment. Maybe it is just me, but I would not want to do a cash-out refi on an existing property unless, in theory, that property could support the re-fi. Which yours cannot. Otherwise, to me, it is not a good investment and I am not making a sound financial move. But maybe that is just me.