Visa run to Macau

Hello,
My citizenship is South Korean and I hold South Korean passport.
I stayed in HK since January 2019; now it is April, and I have three weeks until expiration of my tourism visa.

I would like to extend this visa until May 2019.

Is it possible to take a day trip to Macau and come back to HK, and get another 90 days?

I searched on the websites and some people do it, and others do via Macau-Mainland China-HK.

But I am on my budget so I cannot be extravagant for traveling two different systems.

What can I do?

Thanks,