Refinance vs cash flow

[Itay Heled]

Hello,

my question: should I refinance? 

trying to wrap my head around a choice I have with a rental property

I recently finish turning a house into legal duplex.

new value is $430,000-450,000

remaining mortgage is $173,000

my mortgage is up for renewal On July 

bank is offering me 2.24 rate two year fix.

cash flow with this new rate will give me about $1000 per month give/take

However, I am considering using the equity to invest in a new property.

I can refinance with B lender at 4 % rate with $1000 lender fee and get $150,000  (cant refinance with bank)

would likely allow me purchasing another property, turn it to legal duplex and get around 500$ cash flow per month.

what is the best way to analyze the numbers and  compare those two  options?