I’ve tried many of these on and off over the years, for fun more then education. There is no substitute to dumping yourself in at the deep end and speaking French as much as possible. In the “heat of the moment” you forget all the stuff you thought you had learnt anyway 
Practice is everything.
One day in 1982 having been in France for nearly a year, when driving I found myself thinking in French, I thought “bingo” but with its nuances, the French language road is a lot longer than that 
I think one can also plateau at certain point.
That said, I think Babel is worth a daily visit and Duolingo (which my wife and I went right to the end of many years ago) is amusing. My wife was a subscriber to Lawless too, but dumped her. I can’t remember why. Nevertheless my wife now speaks excellent French (though will modestly deny that).
I think (sexist comment alert) that girls are more fastidious about grammar and accent than (us) boys.