I don't think it's so much slipping back into the I-IV-V, so easily as it is forcing yourself to get away from it. I know you asked for ideas which is fine, my point is, are you forcing it?
IOW, don't put a chord in somewhere just for the sake of doing so. ie: Don't be different, just to be different, so-to-speak.
Tonality in and of itself is seemingly mundane, but think of the gazillion tunes we have just from those three chords you find yourself going back to.
Rest-Tension-Climax-Resolution (I-IV-V-I)
To use the uninvited guest quip: "You ain't gotta go home (I), but you gotta get the hell outta here" (which means you'll eventually go home)
Do you wanna go straight home (cadences: V/v-I/i; IV/iv-I/i; viio/bVII/VII-I/i) or make a few stops along the way? (cadences with more chords: IV-iv-I/i; V-V-I/i; bVI-bVII-I/i; i-iv/ii%-V-I/i).
Seems like you wanna make a few stops along the way or stop by home if only just to visit. :)