Juleika still only goes to sleep on the breast or by holding and rocking her

(on two ocassions only, she fell asleep on her own in her cot!!!)
I am not sure what to do and if there is anything I can do to change that?
I do not want to do the controlled crying thing and I don't have a problem with lying down together with her and let her fall asleep on the breast!
but I just wonder, does this stop by its own? I mean, if she is two years old, will she still need the breast to fall asleep???