Consult the university handbook or speak to the admissions office to determine who you should send your readmission letter to.
Write the letter in business letter format.
Identify yourself and why you are writing the letter.
Apologize for previously not fulfilling your duties or completing your studies, whichever is the case.
Address the issues that lead to your dismissal or withdrawal from the program. If you were dismissed, discuss how you have remedied the problems that caused you to be dismissed. If you left voluntarily, discuss the reasons for withdrawing and explain how they are no longer a factor.
Ask to be readmitted to the program, and explain why you would be successful this time. If you have received a recommendation for re-admittance from any professors, present that information in your letter.
Close the letter with a standard formal closing statement. Sign and submit the letter.