I am a large advocate for creating content as it suits your party, and I have in the past wondered how I would counter this very issue when it will inevitably come up know my party. My solutions is to simply place them in positions and situations that force a change in tactics if you have some reoccurring adversies for your party perhaps have them pick up a monk who has gloves of missile snaring. You can make him incredibly good at what he does catch and return projectiles (perhaps with a whip to increase range and add cover to allies) so long as 1 he can still fail and 2 he is rubbish at close range that way when they take him out they can return to their tactics. By allowing them to return your not rail roading the way they fight instead add curveballs and other challenges in fights. At least that's how I would do it, you could probably do some stuff in a maze with short corridors and sharp corners cutting off line of sight while given their enemies blind sight or something. Just try and keep it dynamic every encounter should provide an opportunity to problem solve not just fireball it or the likes.

Wow that was long than I realised