First of all pls make sure that ur iTunes is set to manually manage music. Then do it as the following dteps:
1.Connect iPod to computer, go to my computer n double click iPod drive, choose "tools" --> “Folder Options”--> “View” --> select “Show Hidden Files & Folders”and click “OK”
2.now right click “iPod Control” folder--> select “Properties”--> un-select “Hidden” and click “OK” --> select “Apply Changes To This Folder, Subfolder And Files” and click “OK” .
3.Next, click “iPod Control” folder and open “Music” , did u see folders labeled F00, F01, F02, F03…? Now Place iTunes side by side w/ this window and make sure that “Music Library” is displayed.
4.In iTunes select “Edit” --> Preferences-->Advanced, and put a check next to: “Keep iTunes Music Folder Organized” &”Copy Files To iTunes Music Folder When Adding To Library”, click “OK”.
5.Then just drag and drop all of the “F” folders into “Music Library” of itunes.
6.last step ,move music to your ipad from itunes.
This might be a little complicated but it definitely works well, and it’s totally free, better than u get a ipod transfer or sth like that. It works for both pc and mac users.
for windows: How to move/transfer my ipod music to PC
for Mac: How to move/transfer my ipod music to Mac