To replace 15amp

Robert,
Please ask your question with a full sentence...
You will then be far more likely to get an answer.

Please use more words to ask a question, and explain why your asking the question.

Short answer is, if I understand your question correctly, you cannot change a 15 amp breaker with a 20 amp breaker unless you confirm all wiring for that circuit is a minimum of #12 copper wire ,or #10 aluminum wire.