Over the last few months I've noticed it takes a lot of pedal travel to engage the brakes on my V70GLT. Could this be a due to a vacuum leak, a defective ABS module, or something more serious? I've had the brakes bled and it didn't improve the problem. When you pump the brakes once or twice in close intervals there is less pedal travel required. Any help would be great!

I think you need to have the brakes bled again really good.Usually when that happens there is air in the system.That is the way to check for air.If you pump twice and the pedal comes up there is air in the system.Which happens from time to time on these cars.

Could possibly be a fault with your servo. With engine off and stationary pump pedal 3 to 4 times. If pedal then stays firm suspect servo and piping if peda still sinks after a brief time I agree with Tech.
Another check of servo operation is to pump 3 to 4 times (stationary/eng off) hold foot on pedal and start engine, if pedal sinks slightly servo seems ok, if sinks a lot servo prob us.
Check the one way valve in the servo first, very cheep to replace.
Hope this helps