I play as a guitarist in my local church, playing mostly contemporary Christian music (Hillsong, Elevation, Planetshakers), and have done for the past ~10 years. I would say that I play at an intermediate level, have a good grip of music theory and have no issues picking up the various guitar licks from listening to the tracks. 

However, I feel like my playing ability has stagnated for the past 3-5 years and find that, when improvising, I end up going over the same sort of thing all the time i.e. picking through various chord inversions, or following the chords with octaves in the livelier songs.

I really want to take my playing to the next level and be more creative with my playing. 

Does anyone have any advice? Particularly any structured courses or books that you would recommend?