I think he originally planned to reunite her with Romeo and then use their love to end the Montague-Capulet feud but when she saw Romeo dead and killed herself...well he couldn't really do anything with her then :L
Friar Lawerence's plan was for Romeo to take Juliet away to Mantua with him where they could live together.
The Friar's plan is to hide Juliet in the Capulet family tomb, where Romeo will later come to retrieve her once she awakens from the potion-induced sleep.
in act 4 scene 1 Juliet arrives at Friar Lawrence's cell to find some kind of help to stop the marriage between her and Paris. Juliet threatens to kill herself if there is no solution to get to Romeo so Friar Lawerence explains his plan to create a potion where she will fall into a deep sleep and pretend to be dead. while eveyone thinks she's dead Romeo would come get her and run off with her and they would be together. Juliet accepts the potion and Friar lawerence begins to write the letter about the plan to Romeo and gives it to Friar John to give to Romeo. Balthazar(romeo servant) sees Juliets funeral and goes off to tell Romeo about it in ACT 5 scene 1 not knowing it was all fake. Balthazar makes it before friar john so Romeo doesnt get the letter about the plan and never finds out that Juliet was never actually dead.
Balthasar ruins the friar's plan by beating Friar John to delivering the message of Juliet's fake death. By telling Romeo before the Friar it caused Romeo to believe Juliet was actually dead.
Juliet asked Friar Laurence to help her avoid marrying Paris by giving her a plan to fake her death so she could be with Romeo instead.
Friar Laurence asks Friar John to deliver a letter to Romeo explaining the plan to fake Juliet's death.
Friar Lawrence devises a plan for Juliet to fake her own death by taking a potion that will make her appear dead. Juliet is worried whether the potion will actually work, if she will wake up in the tomb alone, or if the potion might actually kill her.
Juliet threat to kill her self
The friar and Juliet can control their actions and decisions within the plan, such as Juliet taking the potion and pretending to be dead. They can also control how they communicate with each other to ensure the plan is executed smoothly. However, they cannot control external factors or other people's actions that may impact the outcome of the plan.
Friar Laurence in Romeo and Juliet, appears to play a small role, because of his mere seven scenes. However, closer examination reveals that the Friar plays a fundamental role in the development of the story. He is a confidant to Romeo, moves the plot, and is instrumental to the tragedy at the end of the play. At the beginning of the play the reader learns that Friar Laurence and Romeo are close friends. After Romeo explains to the Friar his love for Juliet, he tells him that him and Juliet must marry to end the feud between the two families. Also, his plan to make Juliet sleep for 48 hours while Romeo comes and takes her away, failed. He is the reason behind Romeo and Juliets death. _NOUR SOLIMAN_
She was anxious and desperate. If the Friar had not thought of a plan her intent was to kill herself, right there.
She threatens to kill herself.