Sounds like you're varying up the melody some more? I think you do a fine job of that already, you have a lot of variation within it. I meant more with the rhythm, or tempo, or harmony, or range, or dynamics, etc. etc.
For instance, your bass line is E then D, right? So it's in E minor, then you have the 7th (D), then you go back and repeat. What if you tried going through the other notes of the scale for a while? Even just swaying back and forth on C and B for a bit would sound cool, and it's a cadence ending on the B for your E minor loop again. AND, if the B chord is major, you get to go with the chord for your sax melodies to fit it, giving your melody variation from a different angle.
What if you dropped that static bass note out for a bit? Less is more. Have just the drums and that killer bass keep the momentum, maybe the sax leads are toned down. Idk, I'm just spewing off ideas from the top of my head.
You'll hear static harmony in rap music, but they have lyrics to focus on. With instrumental music, sometimes you have to take extra measures to maintain interest in looped music. Just my opinion though, I'm just some dude on the internet.