Refinancing $149000, conventional 30fix, 4.4990% interest

[Vannak Kann]

Hi all,

I have a rental home which I currently owe $149000, conventional loan 30fix at 4.9900% interest rate that I bought since 2013. I'm thinking of refinancing it to lower the rate, is it worth it to refinance and paying all the fee. I plan to hold this property as rental for a long time. 

If it makes sense to refinance, Should i refinance to 15 fix or 30fix?

Assuming I can get 3.5% for the conventional loan. Should i just keep it as it is?

Thanks,