I booked a SIN trip a while back, on a W fare.

I'd now like to change the outbound leg to one week earlier, and keep the return date the same. There was a schedule change on the itinerary so I could probably get United to cancel the ticket without penalty, and then I could purchase a new ticket for the dates that I would really like.

Unfortunately it looks like there are no W fares left on the return date that I want, which means a new ticket would cost an extra $400 or so, which I would love to avoid if possible...

I was wondering... if I cancel my ticket, does that mean that the W fare bucket for those flights would go up by one? If it does, then perhaps if I'm quick I could buy the new ticket and get that W fare...

Has anyone tried that?