I would suggest that the best approach is to use an editor to change the biome of all the chunks in the area to be the same, without changing the blocks on the chunks.
This will make the grass in the village to be consistent.
There could be side-effects, for example certain mobs only spawn in certain biomes.
I expect that this could be accomplished with MCEdit. You would need to stop the server, then open the world with MCEdit, change the chunks to be a different biome, then save, then start the server back.
Alternatively, it may be possible to use WorldEdit which is a Bukkit plugin. I don't actually know if it allows changing of the biome, you'd have to look into it. Either way, I suggest you consider installing WorldEdit anyway. It is very handy to be able to copy/paste whole buildings, or generate a huge wall with a few commands.