Swap out the chain. The style of chain used for the pendant gives a context to the necklace. Mixing a sleek pendant with a textured chain instead of a sleek chain, for example, can change the whole personality of the piece. You could also try nonmetallic materials to hang the pendant from, such as leather, silk, rubber, rope, strands of beads or pearls, or twine to create an overall effect that speaks volumes about you.
Use a different metal or a combination of metals. Green gold or rose gold can make a standard design look fresh and new. You could also use two colors of metal with the same pendant, such as copper and silver or white and yellow gold.
Change the stones, especially if the pendant features more than one stone. The same basic pendant can become fun and funky if it contains an unexpected yet harmonious combination of stones. Take a pendant with a colored oval stone ringed by small diamonds, which is about as basic as it gets, and swap out the stones for an oval citrine or peridot ringed by small round amethysts -- same design, totally different effect.
Engrave a personal design or statement onto the pendant. Engraving adds an element of texture that takes a pendant from ho-hum to spectacular. A personal word or phrase makes it a piece that has a special meaning for you alone.
Wear your pendant in a different way. Layer it with other necklaces, use it as the clip in a lariat or even wear it facing backward with a top that has a plunging back. Use your imagination and present it in a way that will have people looking at it from a new perspective.