Um, it can be done from in game, and without del the -dim 1 folder. However you must have the plugin World Edit, as most servers do.
Its rather ez
- Go thru the end portal.
- //wand
- left click on one corner of the end platform
- go to opposite corner ( least 200m away) and make a pile of blox roughly 20 high
- right click top block on yer pile
- //regen
poof, everything in that entire area is as original way, hurry n /spawn b4 the dragon can generate and it wont even be there til a new player comes thru the portal.
This way any structure you built out in the end away from the main platform are saved intact