Having flown with ThomsonFly 3 times in the past month I'd say they'd be more inclined to remove an aircraft rather than add another. Ok, so it was midweek, it's winter, but the loads were very poor.
On the other hand, i've also used easyjet to Geneva and i was pleasantly surprised by the numbers.
Outbound on a Wednesday = 90-100 pax
Inbound on a Sunday = 134 pax
Here's hoping for more !!