By resetting your character, you've reset your Solstice quest, which is what controls you being able to meditate. You're most likely on the step to upgrade your blue set, so you can try pulling it from your collection, and if the objectives are already complete, equipping the set should advance the quest to where you can meditate to upgrade to the purple set. You'd then be able to put on your completed purple set to advance the quest again. If the blue set objectives aren't already completed, you'll have to do them again, and go from there.