Use a metronome. Both to keep steady time and to challenge yourself to play with increased speed.
As a high school student, I ran middle distances for my track team and was introduced to a world carefully measured in minutes and fractions of seconds. Our coach, Bob Bowersox, kept meticulous records. He recorded our race times, of course, but he also kept records of our workout times as we ran repeated intervals of 440 and 880 yards and he encouraged us to do the same. Thus, over the course of a season, we had proof of our individual progress as race times and practice times got faster and faster.
It’s a strategy that applies to guitar work as well – one my daughter, Maia, used as she became an accomplished violinist and later a pianist and guitar player. I occasionally give myself “time trials” and record the results in metronome-measured beats per minute in my music book. It’s a confidence boost to document that songs and scale exercises I initially struggled with are becoming faster and smoother. At the same time, using a metronome helps me push myself toward these kinds of improvements.
The main reason to use a metronome, though, is to help develop a sense of steady rhythm. Set the metronome for a beat you can handle and play along with it. The metronome will remind you not to rush easy passages, and it will also help you identify places where you stumble and need more work.