DERRY, NH (AP).- From Highway 28, the New Hampshire farm once owned by poet Robert Frost may seem unchanged from a century ago. Yet the picturesque New England white barn and farmhouse recently underwent thousands of dollars in renovation including a new roof, foundation work and other upgrades. And for the first time in decades the Robert Frost Farm — which sits on 30 acres in Derry, N.H., about 10 miles north of the Massachusetts border — now closely resembles the place Frost left as he embarked on a life as a full-time poet, officials at the historic site say. This year marks the 100th anniversary of when Frost sold the poultry farm for $1,100 to help pay for a three-year adventure in England where he would begin obtaining recognition in the world of letters. After walking away from the farm, Frost won four Pulitzer Prizes for poetry, read at the inauguration of President John F. Kennedy and received a number