I Have Been Diagnosed With CHF And Had High Blood

i have been diagnosed with CHF and had high blood pressure. I am on meds and blood pressure is under control. however I was on 1 dose of lisinopril and it was working fine..my blood pressue would be around 95/80(ish) but in the afternoon/evening the sys number it would go up some, nothing major. the last appointment the dr doubled my dose...why would they do that?