This usually means something has changed, either competition has increased, the audience has shifted, or the landing page is not working as well as before. The first step is to check if your cost per click has gone up, then look at whether your conversion rate has dropped. If clicks are more expensive but people are still converting at the same rate, the budget needs to go up. If the conversion rate dropped, the page or offer needs attention. So what do you think is the first place to look when costs go up but results stay the same?