[ponder]

I'm guessing you play d? If you're skating forwards towards and attacker, and he's skating towards you with the puck, you basically have 2 options:
1) Quickly stop and start skating backwards, your first couple backwards strides should be backwards crossovers, that's the quickest way to accelerate backwards from a stop. It doesn't need to be a full stop, it can be a sort of partial stop/turn that leads immediately into a backwards crossover
2) Just keep skating forwards, and try to aggressively strip the puck from the attacker

Honestly, neither are great options if an attacker is bearing down on you under full control of the puck. Changing directions means you lose too much time/speed, and stripping him straight up will be tough if he's a good player. Just try to avoid this situation, you should only be aggressively skating forwards to get the puck if you're pretty sure you can get it, otherwise you should be playing safe, positional hockey.