I'd like to turn Debian into Ubuntu server 16.04. Problem is that its running on ARM9 32bit processor with some archaic hardware and I don't want to make new installation.

How should I modify /etc/apt/sources.list to be able to install new software preserving old drivers?

Maybe I should keep old kernel and just install side packages that do not require kernel modifications?

this is what I get from cat /proc/cpuinfo

Processor   : ARM926EJ-S rev 5 (v5l)
BogoMIPS    : 183.09
Features    : swp half thumb fastmult edsp java 
CPU implementer : 0x41
CPU architecture: 5TEJ
CPU variant : 0x0
CPU part    : 0x926
CPU revision    : 5
Cache type  : write-back
Cache clean : cp15 c7 ops
Cache lockdown  : format C
Cache format    : Harvard
I size      : 32768
I assoc     : 4
I line length   : 32
I sets      : 256
D size      : 32768
D assoc     : 4
D line length   : 32
D sets      : 256

Hardware    : Oxsemi NAS