Its a little late for “God save the Queen”.
More like, “I pray that the Queen accepted Jesus before she died. Then God will save her because she’s already been saved”.
Why would you think she hadn’t accepted Jesus since her birth? By all accounts, she was a devoted follower of Jesus Christ her entire life.
In her Christmas 1952 Message, her first Christmas as Queen, she asked the people of the UK and the Commonwealth to, "'Pray for me … that God may give me wisdom and strength to carry out the solemn promises I shall be making, and that I may faithfully serve Him and you, all the days of my life.’
Here is a link to an article appearing in Haven Today titled "10 Surprising Things the Queen Said About Jesus"
It would seem that God has saved her, and many decades ago. Praise God!