Progression is about more than just adding weight to the bar. That's just one way of progressing. There are several other ways:

  1. Do more reps with the same weight.
  2. Do more sets with the same weight.
  3. Increase density. Cut time off your rest periods or use active rest instead of passive rest.
  4. Increase the quality of each rep. For example, explode the weight up better.
  5. Improve mental focus.
  6. Use intensity techniques: supersets, drop sets, rest-pause, etc.

Related:  Make Progress Without Adding Weight

Related:  Nonstop Natural Gains: The Neuro Typing System