Players can hit a slump just like Dungeon Masters can. However, the ways to deal with them tend to be very different due to the nature of the role. In some ways, players have more tools to work with. In others, they aren't nearly as free. For this reason, I'll be talking about it in this separate post than the one I did focusing on the Dungeon Master side of the screen.
Being the Dungeon Master
Making the switch to Dungeon Master could help get over the slump. The role is vastly different so some people really do enjoy the large change. However, it's also a large commitment and usually needs more preparation time than being a player. You don't really want to start a campaign you don't think you can finish. I think it's also far more common to have Dungeon Masters who have previous experience as players than players who have previous experience as Dungeon Masters (though I have met the occasional Dungeon Master who started in that role and never left). This lack of experience can make things quite a bit tougher at first and more stressful. It's not that the switch can't be done or that it's necessarily a bad idea, but I can't blanket recommend it. It will depend heavily on the player in question.
Playing a New Character
As a player, your character has a large impact on your game. It's also quite common to fall into a pattern of making rather similar characters. These similarities are usually the personality of the character, or the class. Either way, trying something new in either of these categories can help make things seem new again. The switch between a martial class, a skill monkey class or a magic class tends to be the most pronounced in terms of changes. The way they handle themselves in combat and outside of it is different enough that it can make the game feel completely different. It often also leads to making different characters to suit the strengths of the new class, though this isn't always the class. Switching up the background of a character can also go a long way due to the large changes and challenge role-playing presents in those cases. It may also be worth thinking about your spell list from an in-world perspective. I also often see (I'm guilty of this too) spells being chosen for their usefulness in combat instead of if they make sense for a character to have. Choosing spells you wouldn't have normally can lead to interesting combat solutions and unorthodox utility use.
Working Through It
There are times in a campaign where things need to be done to lead to better and newer things. Sometimes it's worth just going along for a bit and hoping things change soon. This will of course depend on your previous experiences in the campaign and whether you can reasonably expect such a thing. However, it's worth considering and thinking about, particularly if you want to keep your character.
A New Twist
Sometimes, all it might take is a new dynamic or event to mix things up. To achieve this, you might decide to plan something with a fellow player. Stories between players can be just as important as the stories between the players and the Dungeon Master. I do need to say that you need to be a bit careful not to hijack things from the Dungeon Master in these cases. You can also try talking about possible twists or events that involve your character with your Dungeon Master. Having your character as a central part of an event has a way of opening up new role-play opportunities. It's important to note, however, that what I'm talking about here is if you are alone in your feelings. If everyone else around the table is feeling out of it, it could be that the campaign needs to be shaken up in general. Adding an event that has your player as a central focus might not be enough. It'll need to be more drastic in scope and involve the whole party.