Apps won't download to discontinued device

HI, I have an app which I purchased from itunes, it's been working perfectly up until I got a new laptop at Christmas and had to transfer my library from my old latop. I have 2nd generation ipod touch, and now when I try to sync the app to it, I get a message saying the software is outdated so the app will now longer sync. I've tried whited00r, but nothing seemed to happen...it's a favourite app and I'm really really annoyed that I can't load it to my ipod! There is a newer version of the app, but it isn't the same (new and improved often isn't improved at all), and I don't see why I should have to pay for it again anyway.

Is there any way to get it back on my ipod, or I'm I doomed forever more....?

Thank you!