First of all, everyone 'always plays the same things'. Even the greats rely on licks once in awhile. Some people make a career out of them. But if you're playing jazz and improvising, I would bet most of us have had this thought a few times about our playing. So, what to do about it? Here are a few things that have helped me over the years:
1) Stop playing guitar! - That's right, put down the axe. Sometimes a little break is all that is needed to gain a fresh perspective on things. Which in turn makes me play a little bit differently. Not necessarily better, but I find my mind is a bit clearer and sharper after a few days off. Plus, there are probably other things you could use the time for (personal hygiene and housecleaning come to mind...)
2) Find new music - Whether you stream, download, or purchase CD's (or vinyl), find something new to sink your teeth into. Ask friends for recommendations. Think about a gig you played where you struggled on a particular song - buy that album. Listen to as many versions of that song as you can. Although I don't subscribe to a streaming service, one of the advantages I can see are automatically generated playlists. These playlists can potentially expose you to all kinds of music you probably wouldn't have found on your own.
3) Lift a solo - Preferably by someone playing an instrument other than guitar. Transcribe a saxophone solo, or trumpet, or try lifting some voicings from one of your favourite pianists (and distilling them down to 5 or 6 notes if needed). Every instrument has it's own idiosyncrasies, and borrowing an idea from someone playing a tenor sax can sound fresh and new when played on a guitar. If you're new to transcribing, begin with something simple and clear that's easy to hear - Miles Davis' album Kind of Blue is a great place to start. I've also found that, for some reason, Dexter Gordon's lines sit pretty nicely on guitar, at least for me. And don't just learn to play it - write it down and analyze it. Find out where these notes came from, and most importantly, why he/she is playing them.
4) Find new musicians to jam with - Sometimes a change of scenery is needed to dig yourself out of a rut. Go to a jam session, or call up that piano player you've never played with and see if they want to do some playing. It's always nice to offer up a gig to someone, but you'd be surprised how many musicians out there are OK with just getting together and playing. The worst thing they can do is say no. Try getting involved with players who play instruments you don't usually share the stage with. When I moved to Casper, WY, I had a hard time finding people to play with. It's a small town and there's almost no jazz musicians. But I met the percussion instructor at the local college, Ron Coulter, and on a whim asked if he wanted to play some duets. It went so well and we had so much fun that we recorded an album!
5) Buy some new gear - They say money doesn't buy happiness, but a new piece of gear can inspire you to play differently. I'm not a gear pig by any means (I've been using most of the same equipment for 20 years) but every few years I'll grab a new pedal. It's fun to learn to use the new sounds, and try to incorporate them into your style.
6) Go see a live show - Nothing inspires me more than seeing master musicians performing at a high level on stage. It reminds me of why I started playing - which leads me to...
7) Remember that music is fun - sometimes just changing your attitude will change the result. Don't forget why you started playing music in the first place.