I'm not used to this kind of physics but I think that when you get far the player shouldn't stop but automatically come back (so maybe it should be impossible to give "thrust" for too long?)
Also maybe, if there could be a way to make it harder to hit stars (and if the player still "manages" to do so, it would be a loss instead of this strange repop).
And then, create more levels to have something easier after the 1st.
That's not easy to enhance/balance, for sure :D But it would deserve it!