If all else fails, there are some brush tools that you can get with Bukkit, then you can run it on a server and level the hill again in mere seconds. Also digging down becomes a breeze :3 It's called world edit, link here, in case you're lazy, haha ;P
http://forums.bukkit.org/threads/edit-sec-admn-worldedit-4-6-world-editing-de-griefing-1000.62/
there's also another one for building more random landscapes, since world edit is more like a "heavy lifting tool", it's kinda rough to use sometimes. One I'm talking about is called LandBrush, it's pretty neat for making landscape and making it look more random like it does naturally when it generates from the seed.
http://forums.bukkit.org/threads/edit-landbrush-v1-2-1-using-landbrush-makes-creating-new-structures-quick-and-easy-1060.34199/
Of course, last but not least, there's VoxelSniper which also works extremely well

It works a bit like the WorldEdit, but it fills the gap between the two, again, link here in case you're still lazy, lol
http://forums.bukkit.org/threads/edit-fun-sec-voxelsniper-v5-019-flexible-long-range-in-game-map-editor-1060.1748/ I know, I didn't exactly help with your savefile-problem, but you should be able to use these to fix it all up again real quick on a new map ;D
Omnom