It all depends on why does she not pray or fast. Thus, if she does not pray or fast out of laziness without denying their obligation, then she is still considered a Muslim – as stated in the Aqidah Tahawaiyyah; a person guilty of major sins does not go out of the fold of Islam unless he or she justifies them or declaring them as lawful.

Having said this, let us not forget that Prayer is the most important pillar of Islam: It is the means of salvation and the key to paradise. So, by neglecting it, one is endangering his or her salvation.

Allah Almighty knows best.