2001 Honda Civic cooling system

i have a 2001 Civic and it has 200k miles on it. i noticed that the coolant keeps on going to the reservoir and not going back to the radiator, hence i keep on adding coolant to the radiator almost everyday. i also noticed that the coolant is being discharged when the car is parked overnight. i suspected that it is coming from the reservoir because the when i checked the reservoir, it is still wet. additionally, each time i add coolant into the radiator, the radiator cap, when opened makes a popping sound, just like when you open a bottle of soda when shaken.

two of the mechanics i got advise from said that the car might have a blown head gasket. now i am torn between having the head gasket replaced + head resurfaced versus having the engine replaced altogether.