Why Lord Buddha didn't stay alive till the end of this "Kalpa" I have heard that Lord Buddha once told Ananda thero that a Buddha can live till the end of a Kalpa, if he wishes so. He did this because he wanted Ananda thero to invite him to live till the end of the Kalpa.

But, Ananda thero did not invite him as Maaraya was inside his head.

My question is, if Lord Buddha was able to read minds and see future, why did he asked that question in the first place ?

Why didn't he lived till the end of this Kalpa himself ?

What I am missing here ?
The Buddha did not ask venerable Ananda to invite him to extend his life. He only hinted that it is possible for him to do so.

Mara's Appeal

And when the Venerable Ananda had gone away, Mara, the Evil One, approached the Blessed One. And standing at one side he spoke to the
Blessed One, saying: &quot;Now, O Lord, let the Blessed One come to his
final passing away; let the Happy One utterly pass away! The time has
come for the Parinibbana of the Lord.

&quot;For the Blessed One, O Lord, spoke these words to me: 'I shall not
come to my final passing away, Evil One, until my bhikkhus and
bhikkhunis, laymen and laywomen, have come to be true disciples —
wise, well disciplined, apt and learned, preservers of the Dhamma,
living according to the Dhamma, abiding by the appropriate conduct,
and having learned the Master's word, are able to expound it, preach
it, proclaim it, establish it, reveal it, explain it in detail, and
make it clear; until, when adverse opinions arise, they shall be able
to refute them thoroughly and well, and to preach this convincing and
liberating Dhamma.' [23]

&quot;And now, O Lord, bhikkhus and bhikkhunis, laymen and laywomen, have become the Blessed One's disciples in just this way. So, O Lord,
let the Blessed One come to his final passing away! The time has come
for the Parinibbana of the Lord.

&quot;For the Blessed One, O Lord, spoke these words to me: 'I shall not
come to my final passing away, Evil One, until this holy life taught
by me has become successful, prosperous, far-renowned, popular, and
widespread, until it is well proclaimed among gods and men.' And this
too has come to pass in just this way. So, O Lord, let the Blessed One
come to his final passing away, let the Happy One utterly pass away!
The time has come for the Parinibbana of the Lord.&quot;
......................................................
-Maha Parinibbana Sutta

Buddhas do as they proclaim, so once the Sasana is well established, the lord would not extend life without an invitation as Buddhas do not have the desire to live on. Besides, venerable Ananda was the one attending to the Buddha. So it is only proper that the Buddha hinted it to him. Also, it was always going to be someone who has not yet attained Arahanthship that should invite the Buddha to stay on as Arahanths have already achieved what needs to be achieved and do not require the Buddha to stay.
Buddhists do not believe in determinism. The future is not fixed in all situations. Only some things can be predicted to happen for sure. The Mara stopping venerable Ananda from inviting the Buddha was not destined to happen. He would have invited if he was able to overcome Mara at that time.
In any case, the word Kalpa here means an Ayu-Kalpa. Which means the Buddha would have lived 120 years at most, even if ven. Ananda had invited.