I know this has been posted before...

[Epistolary Richard]

Don't worry, I've lost countless bits of useful information somewhere in these forums (if only someone could point me back in the direction of that site with the unit stats and the cool interface with pictures of troops from all the different factions on the front page *sigh*).

The range of javelins is set in each individual unit's stat description in export_descr_unit.txt:

type             roman velite
dictionary       roman_velite      ; Velites
category         infantry
class            missile
voice_type       Light_1
soldier          roman_velite, 40, 0, 0.8
mount_effect     elephant +6, chariot +6
attributes       sea_faring, hide_improved_forest, hide_long_grass, can_sap
formation        1.6, 2, 3.2, 4, 3, square
stat_health      1, 0
stat_pri         7, 2, javelin, 50, 6, thrown, archery, piercing, spear, 25 ,1

That '50' in the bottom line is the range.

Now you can go through the .txt file making changes to every javelin-equipped unit (a find and replace for javelin, 50 should do it), or you could explore the possibilities of GodsPetMonkey's Caligula unit editor programme about which you can find out more here.