Jude, the servant of Jesus Christ, and brother of James, to them that are sanctified by God the Father, and preserved in Jesus Christ, and called. JUDE 1

To be 'preserved' or 'kept' in Jesus Christ does not mean you are saved and can never lose your Salvation - that your Salvation is safe for as long as you live. It does mean that assuming you have come to Jesus Christ and been born again - He will now try to keep you with/in Him by disciplining and correcting you. You are only preserved in Jesus Christ as long as you are abiding in Him and allowing His correction and tutelage. If you go astray (and so abide in death!) He will try to get you back with/in Him in the land of the Living but it is up to you whether or not you choose that Life.

God can't preserve or keep anyone against their will. If you choose His discipline you are receiving His Salvation. If you reject His discipline you are rejecting His Salvation.

I guess it's all about Love. God's Love to you is His discipline and correction and your Love to Him is your submission and obedience, that is to say your repentance.