you need to call addEventHandler only once, and you have it in a loop.
wepcol = createColCuboid ( 1495.6212158203, -3100.0891113281, 87.07982635498, 5, 5, 5 )
root = getRootElement()
function render()
dxDrawText("meep",329.0,412.0,482.0,425.0,tocolor(255,200,0,255),0.9,"default-bold","left","top",false,false,false)
end
function enter()
addEventHandler("onClientRender", root, render)
end
addEventHandler("onClientColShapeHit", wepcol, enter)
function leave()
removeEventHandler("onClientRender", root, render)
end
addEventHandler("onClientColShapeLeave", wepcol, leave)