What needs to be done is slightly detaching income from military. Basically, not all untrained should produce income anymore. To reach this goal, you could have a stat named mining capacity that is upgraded in a manner similar to unit production. The mining capacity is the maximum number of units that can provide naquadah. If you're over the limit, losing units won't matter all that much. So, losing units will be much less of a factor in long term profit.
A second benefit of this approach is that you can finally implement the unit production bonus for one of the races without too much of a balance problem. More units no longer means more income per se. It means more units to waste on attacks, sabotage, the fun stuff
An example (hypothetical stats):
I have a unit production of 300
I have a mining capacity of 10000 units.
I have 9800 units.
Right now, I have 10000 mining capacity, so I could send 10000 units into the mines. But I only have 9800 untrained, so my income is 9800*40=392000, or 490000 for a goa'uld.
By tomorrow this time, I'll have 10100 units. I can send 10000 into the mines and get a turn income of 400k, or 500k for goa'uld. The extra 100 units are just sitting there, doing nothing, so I could just as well train them for some other task. I won't notice a change in income.




