I would like to see this expanded slightly in Victoria 2 if possible.
One of the key ways military planners controlled the strength of the army was through military service, and this was something that did not feature in the original Victoria.
It should not be operated in the way it was before, where you make a one off payment of resources (small arms and canned food IIRC) to increase you Mobilization pool. In reality, these levels were set through 1 year, 2 year or 3 year drafts (ala Hearts of Iron 3)
Perhaps it would be possible to simulate this, and link it to the political reforms? In this way you could model the traditional British reluctance to introduce conscription (the idea was frequently floated in the pre WW1 years but politics prevented it from becoming a reality)