Cash Out Refi or Hold the current Loan?

[Trevar James]

Hello community, I'm looking for a little advice. I just moved in tenants at my first rental prop. Its generating about $500 cashflow after mortgage, mat, and vacancy. I purchased the house as a foreclosure so after a few repairs I should have a really nice amount of equity. I was wanting to move foward with the Brrrr strat but I'm hesitant thinking if i refi to a bigger loan won't it kill the cashflow Im getting. Should I just stay with my current loan or am I looking at it wrong. 

Oh and the loan is a conventional with a local bank as a second home 3.35% interst rate if that info makes a difference. 

Thanks Beforehand for any advice.