Why is magma and lava in core does not get finished after the thousands of eruptions???

When an eruption occurs some part of our core is realised, out affter an eruption again the process of making magma is started, but to melt that elements there are some way to melt that eliments .

1 Heat of deapth
2 And radio active eliments like uranium and
thoranium

This all things helps to core to regenrate magama and lava .

And because of regenrating of magma and lava
There is no reduction can be seen in the earths core.