How your profile works
Each time you finish a game, your browser records the result: your best score for that game, stars for the level, experience points and, if it was the daily challenge, your streak. A streak counts the days in a row you have completed a daily challenge; miss a day and it starts again at one.
Because the profile lives in your browser, clearing site data removes it. To keep it, copy your export code and paste it on another device, or keep it as a backup. You can merge an imported code with the profile on this device so you never lose your best results.