A lot to talk about in that topic. I remember being influenced a lot when reading the composition part of the book Poetics of Music by Stravinsky (http://monoskop.org/images/6/64/Stravinsky_Igor_Poetics_of_Music_in_the_Form_of_Six_Lessons.pdf ). A reference we get from school. A lot of what is mentioned i found true by comparing his thoughts to what i like the most. Also by reading other art field documentations, i believe music to be, in a way, a key to the other fine arts since its essence is only spacial and not visual (more pure in a way?) and also because it is probably one of the first art forms it has more maturity.
I recently try to develop something in a certain care for unity rather than variety. In my current act i show a variety of different techniques that i now believe being easy and less powerful. It produces an immediate effect but similarity (the same idea ZakMcAllister mentioned by the word theme) satisfies us in the long run, in my opinion. So i would be focusing on trying to develop a single juggling technique, i would make it progress in time by the composition, the physicality, the character or whatever people's approach towards the juggling. That is where i am now about composition.
That said, something that I hear Jay saying often is that the more you acknowledge elements in an act, the better. So i also try my best to have a justification for as many choices i take.
In general i struggle often too, i feel that most of the stuff i do is not good enough even though i would reflect on it a lot. I don't know how much people feel the same. But i think it could come from a constant anticonformism to your own opinions, in order to go further. In those moments of struggling, it often brings me back to the essence of the work. where do i find pleasure? it surely is a right direction.