It occurred to me after my last post that maybe you weren't referring to the weekly renown loss, but rather the renown "subtraction" that happens every time you gain renown (ie, the idea that as your renown gets higher and higher, it also becomes more and more difficult to gain new renown).
If you want to change
that part of it, go to your
SCRIPTS.TXT file and find the following:
change_troop_renown -1
31 21 1 1224979098644774912 22 1 1224979098644774913 520 3 1224979098644774914 1224979098644774912 7 4 0 32 2 1224979098644774913 0 2133 2 72057594037927940 1224979098644774913 2123 3 1224979098644774915 1224979098644774914 200 2106 2 1224979098644774913 1224979098644774915 2111 2 1224979098644774913 0
By default, your existing renown is divided by the
200, then the result is subtracted from the original renown gain. For example, if you won a battle with a renown value of 15, and your character already had 2000 renown, you would only actually get +5 renown at the end of the battle (ie, 2000/200 = 10; 15-10=5).
If you wanted to modify the amount of renown that gets subtracted from each renown gain, simply change the
200 to a different value. For example, if you change it to 400, you would still have
some renown taken away, but only half as much as usual. Likewise, if you wanted to completely
eliminate the renown subtraction, you would change the
200 to a very high value, such as 999999.