Sipping DAT LEAN,SIZZURP, TEXAS TEA, PURPLE DRANK?
Lol I kid I kid, but I'm pretty sure codeine has a ceiling limit to it's effect and availablability right at around the 500mg mark. If my math is correct... 120ml is 24, 5ml doses of 10mg codeine and 6.25mg prometh, which means you've only had 240mg codeine and something like 150mg prometh (way to lazy to bust out the calculator or actually think about this one) and tbh that's pretty much just a recreational dosage for someone with just a small tolerance so I think you will be just fine killing the rest of the bottle, as it's only 120mg more codeine making your whole dose about 360mg which should be just fine.
oh and I doubt you are really going to feel much from it though anyways, because I find codeine effects don't really stack when you redose.
I'da saved it for another day and just chugged the 120mg codeine dose all at once.