First and foremost it hasn't been 72 hours yet...
, and by visible signs we don't necessarily mean a bubbling airlock.
It IS a sticky at the top of the beginners forum for a reason, afterall.
Secondly you don't know what's going on....all you know is you have what you define as a "visible sign of fermentation" by which your more than likely mean your airlock is bubbling or you still see krausen... (I'm betting airlock bubbling.)
Your HYDROMETER is the only BEST indicator of fermentation activity. Nothing else is accurate or consistent...
Unless you take a gravity reading you don't know what's really going on, not by airlock bubbling or by krausen formation. Neither of those signs are effective, they don't tell you exactly where on the fermentation process you are.
The amount of krausen can vary for whatever reason, it can come quick and depart quickly or it can linger long after fermentation is complete, and it all be normal.
And airlocks sometimes bubble or they don't.
Fermentation is not always "dynamic," just because you don't SEE anything happening, doesn't mean that any-thing's wrong,, and also doesn't mean that the yeast are still not working diligently away, doing what they've been doing for over 4,000 years.
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?
Besides, With lagers everything is slow and there is often little visible "actvity."