Airlock bubbling starting suddenly doesn't necessarily mean fermentation has started, nor does airlock bubbling stopping suddenly mean that fermentation has stopped. You really need to grasp this fact and seperate airlock bubbling in your mind from fermentation.
Your airlock is not a fermentation gauge, it is a VALVE to release excess co2. To keep your beer off your ceiling. Nothing more.
That's why you need to take a gravity reading to know how your fermentation is going, NOT go by airlocks, or size of krausen, or a calendar, the horoscope or the phases of the moon (those things in my mind are equally accurate).
The most important tool you can use is a hydrometer. It's the only way you will truly know when your beer is ready...airlock bubbles and other things are faulty.
The only way to truly know what is going on in your fermenter is with your hydrometer.
Like I said here in my blog, which I encourage you to read, Think evaluation before action
you sure as HELL wouldn't want a doctor to start cutting on you unless he used the proper diagnostic instuments like x-rays first, right? You wouldn't want him to just take a look in your eyes briefly and say "I'm cutting into your chest first thing in the morning." You would want them to use the right diagnostic tools
before the slice and dice, right? You'd cry malpractice, I would hope, if they didn't say they were sending you for an MRI and other things before going in....
Thinking about "doing anything" like repitching, or bottling, or racking, without first taking a hydrometer reading is tantamount to the doctor deciding to cut you open without running any diagnostic tests....Taking one look at you and saying, "Yeah I'm going in." You would really want the doctor to use all means to properly diagnose what's going on?
Sorry but that really is the only answer that is accurate or consistant, the numbers on the little stick. I have had evrey airlock bubbling/non bubbling/slow bubbling/fast bubbling/little krausen/big krausen/slow forming krausen/krausen staying 3 weeks after the hydro showed terminal gravity scenario imaginable in nearly 1,000 gallons of beer, and none of that stuff is as sccurate as 30 seconds with a hydrometer.