Is there any possibility to replace current dietpi-software package deluge with new version (v.2 ?) Current version is rather obsolate and v.2 appears few months ago after years of no updates.

We install it from official Raspbian/Debian repo. v2 made its way into unstable/Sid branch:
If you find some packages or want to try the ones from Sid branch, it should be possible to simply upgrade the existing ones. However note that the Debian Sid repo will not work on RPi1/Zero due to armv6hf architecture incompatibiity.

However as long as there is no offical Deluge repo or compiled packages, we will stay with Debian/Raspbian stable repo.