I dont know why new levels should change anyones plan to stop XP chasing at level 75 - no reward or pressure for anyone but oneself to level up. If you decided to stop hunting XP at level 75 ( or any other level ) then do so
And regarding new contents - someone made me look in trade - if you search in price you can select a ( unknown to me at least ) new adventure - called 'colossal cave'. !!