
A part from the fact that you lose horrendously just from moving your units around (no battle before T7) you can see that the replacements process just works fine.
In the "T" columns, you get the total strength of each major corps at start of each turn.
In the "Diff" column, you get the difference of strength between two turns (in red if negative).
The procedure in order to get replacements is quite strict. The corps must be either in a city or a camp. Immobile for a full turn and in a non agressive attitude (passive or defense). Then, at the start of your next turn, the strength should have raised.
You will also notice that the replacements' range is quite variable.
Sometime, you have less than 50 reps. Sometime you get more than 12,000

Replacements definitely work OK.