If you alter the auto-angle speed by using the .speed xxx command, it will reset to the default value when you launch a new plane.
FWIW- auto-angle can also be useful in controlling descent speed, rather than being used purely as an auto-climb command. In particular, if you have some altitude to play with it comes in handy in bombers if you have fighters pestering you. Set the .speed to 300 or so, and engage it. You'll go into a slight dive, but won't exceed 300 so your wings wont pop off. Now, hop in the tail gun, and steer if you need to with the rudder...
With your higher speed, fighters will find it more difficult to maintain safe attack angles, and you'll often find them reduced to attacking from your six...