It's your decision really and how you like to play.
Personally I play DiD or Dead is Dead mourn the loss of that boat and start a new carrier.
It puts more "weight" into caring for your crew and will make you a little less cavalier.
Eventually you will be killed again but such is the lot of the Uboat crew
I like to start early in the war and see how far I can get. GW really makes it even tougher because renown is more difficult to come by.... Lots of fun !