There are a lot of options really. The simplest is simply dropping back to a weight you were using 4 weeks ago (assuming 4 weeks ago was a relatively easy weight), and then jumping 2.5-5 pounds/wk. again and moving past your plateau.
You could also go into a peaking stage, where you reduce the overall volume by doing 3x3 (9 total reps) with heavier weights. That might be enough of a deload on that lift to help you get back on track. So, maybe transition into 3x3 for a handful of weeks, followed by a week off on that lift, and then back to 5x5/1x5 setup, ramping up again. Just be cautious that you don't start really grinding and grinding rep after rep for weeks on end as you try to set new records on your heavy triples. You can burn yourself out pretty good. Hit some new PRs, then take a break.