The first 15 minutes of the frame a person can reup do to crashes, ditches, bails, disconnects and friendly fire. They can not reup if they take any damage at all from enemy planes.
This first 15 minutes is the mulligan rule. In frame 1 the default setting of friendly collisions was on resulting in people spawning and blowing up. Also in frame 1 and frame 2 many allied pilots tried to take off in F4U-1Ds with 2 1000 lbs bombs and crashed several times before they managed it. The F4U-1D is a beast to take off with bombs for many.
So to answer your questions yes, you only have 1 life but for the first 15 minutes you can replane unless you have been shot by enemy fire to cover other eventualities. From 15 - 30 minutes you may reup if disconnected and taken no damage from enemy planes. After 30 mintues no reups unless special rules have been put in place by the ADMIN CM (the one who designed the event).
In this event B5N and D3A1 pilots got two lives to use during the whole frame.
Hope that answered your question.