It was 1976 when the New York Philharmonic, in an effort to improve the acoustics of Avery Fisher Hall, gutted the place and mounted a huge renovation. It didn’t help much, and last year, the Phil, not wanting to run the risk of another unsuccessful construction project, attempted a merger with Carnegie Hall. The merger fell through very publicly when the boards of the two organizations couldn’t reconcile their schedules and goals, and the orchestra was once again stuck with Lincoln Center. Now, the plan for a new renovation of Avery Fisher is back on, at an expected cost of $300 million. Construction won’t begin until 2009, and the Phil will have to find a new temporary home for a couple of seasons during the renovation.