Try adding a new pricing plan that is much higher than the others you currently offer, making the rest look more affordable and a better value for money. If this new plan is significantly higher than whichever plan you favor (hope that the most people will buy), it will make it more reasonable and really like a great deal in comparison.
The philosophy behind this test is the decoy effect where you add an additional decoy item to influence a purchase decision. In this case, you suddenly make the middle plan (or whichever you prefer) much more appealing and it stands out as the obvious choice, resulting in more sales. Usually when we are buying stuff, we compare with other offers and make an informed decision (at least what we think) - the same goes here.
In this A/B test, you should add a significantly higher plan to your existing offer, making them look much more affordable. Your site visitors will feel like they are getting better value for money because they are saving a lot in comparison to your decoy option.
To make it perform even better, add tags like "Most popular" or "Last purchased x time ago" to influence the buying decision even more. The decoy effect makes us compare all existing options and decide the value of something, so you need to make your middle plan stand out.
