A 6 pack is not something you can train for. The key is: fat % around 10% or lower. You can always do the 'fitness' exercises to train your muscles, but the key lies in a low fat % and a healthy diet. Good luck!
Also, if the Gilette 5 blade razor isn't working for you after trying anything spcified above, you should consider getting a different blade. I hear Edward Jagger DE89L gives a good shave. And the advantage is that you can choose from a range of different blades, suitable for different skintypes.
First calculate how kcals your body need in a day if you don't do any exercise. Then eat 10% to 20% less than what yourn body requires. Do cardio every day ~40 minutes, and you will be back to your old self in a few months.
And ofcourse only eat the healthy stuff, no fastfood, enough vegetables and fruit.
Just my 2 cents