meaning of "for a while now"
He has done little of that for a while now.

Question

Answer

It means he has not done it very much for a long time. So he used to do it a lot, but lately he has only done it a little

Answer

He has done little of that... here the "that" refers to the action (the unknown thing he has been doing in this sentence)
for a while now.... referes to the time period. It implies quite a long period of time in this case.