Do you think it is a good idea to buy superstar whenever you run out?
In short yes I do. Mostly because their is not much to do when you are not a superstar. What I like to do is wait a couple days, and then refresh my superstar. I recommend trying to get the 6 month superstar, its not as expensive as the 1 year one. And if you are used to getting the one month one tell your parents that the 6 month one will be better because, you wont ask for 6 month and its cheaper then paying $6 a month.
Also before buying superstar, consider a few things.
1) Is it worth it?
2)Will I continue playing stardoll when my ss ruins out?Or while Im in the middle of my SS membership.
Hope that was helpful!