leaky windows - best course of action?

dementedfeline

So, it appears that when the wind comes from a certain direction and it's raining hard, there are several window panes where the putty has dried out or something, leaving a gap = puddles on the inside.

Do I slap more putty on now or would that potentially make the problem worse by enclosing already wet wood? Slap on now, wait for dry weather, expose, hope the wood dries out and then reputty/paint? Something else? Win the lottery and get double-glazing?

Thanks