Except means "everything but". Is there a single word in English that has the opposite meaning to that of "except" (an antonym of except)?
Mathematically, we might argue that if "except" is defined as "everything but", then we must have a universe X say, in which we want everything but except some A. So an antonym of "except" woud be "only" - we "only" want A and nothing else from X.
Another option, to describe extra elements, might be "additionally":
Put everything on my sandwich except for pickles.
Put everything on my sandwich, and additionally some pickles.
Although in normal conversation, this would usually be said in a less technical way:
Put everything on my sandwich, and please add some pickles too.