If you have a copy of the Remote app in your iTunes library that is compatible with your iPod delete the app from your iPod/iPhone and sync the app to yur device.
If not, delete the version in you iTunes library and transfer/copy the app to your iTunes library by
There is no way to the later version on your devices.
It's a pity Apple won't make old software available for iOS as they do for old Mac OS computers. I still run computers over a decade old, but can't use a 3G with 4.2.1 to send music into my airport express without a plug and wire into the amplifier. I sent feedback. I have no backup version of Remote as this is an old iPhone that wasn't mine originally.