The truth is,without constant challenge you will plateau very quikly(feel like your not getting better).In some players(myself included)that plateau can only be broken in two ways.

1:Constant learning and challenge.
2:Actual growth as a human being physically and mentally!Isn't that crazy?It sounds it,but I broke one plateau just that way...I approched the guitar as a different person due to human growth!

The second one isn't forced and can't be induced(in any way I know of...dont confuse human development with learning...your growth is affected by learning no doubt,but the natural progress of youself is determined by billions of variables like genetics,biological chemistry e.c.t.)

So...ah..just practice and dont cease learning cause that second one there is uh...not..easy.