Did you fail to maintain a backup copy of your computer?
You can transfer them from the ipod> File>Devices>Transfer Purchases
Or you can redownload them. You do not need itunes to let you do anything. this is a standard feature:
If you are still using the same Apple ID then go into iTunes store on your neww computer. Click the purchased link under Quick links and it will show everything you have purchased.
To redownload at no cost click on the cloud symbol by the item and it will download.
When you have worked your way through them all you can sync your ipod with your new computer. It will Erase and sync, Then just sync back on whatever you want.