Potassium/Magnesium Protocol?

Hi I'm still a relatively new nurse and have a question about something. I know generally this may be a hospital driven protocol but I want to know how others do it as well. For potassium and magnesium, once you replace it and schedule the redraw and then you get the results. Could you give another dose of it depending on the results? Hypothetically if potassium was 3.1 I gave 40 of potassium orally and redraw 4 hours later. It's 3.4. Would it be correct to assume to give another dose and schedule another redraw in 4 hours? If it fit the protocol and the patient is the same clinically? I did not see anything about this in the protocol just replace if it is this result, etc and redraw in so many hours.