Hi, welcome to iMore.
If you had purchased all your songs on the iPad from iTunes, you can download them to your iTunes.
From iTunes on Computer
Open iTunes and select ?iTunes Store?.
On the right menu, click the ?Purchased? link.
If prompted, type your Apple ID and Password, then select ?Sign In?
Select the type of item you wish to download at the top-right part of the window. Choose ?Music?, ?TV Shows?, ?Apps? or ?Books?. You can also choose to view ?All? or items ?Not in My Library?.
Select the Cloud icon next to the item or the ?Download All? button located at the lower-right part of the screen to download the item(s) to your computer.
Than simply sync your iPad with iTunes.
If you have any questions left, join our forum and ask away.