There is no way of singularly answering the question because there is no such thing as one protestant church or one megachurch being identical to another, not even if they necessarily belong to the same denomination or group of churches. You need to remember that protestant/evangelical Christianity is not hierarchical or apostolic.
Sometimes they go up if they want to recommit. Sometimes only if they want to be baptized for the first time. Sometimes a combination. It all depends. In my original church, which was a Church of Christ, people were baptized once they decided to be baptized (I was 11) and then people could also speak to the pastor about publicly recommitting themselves.
In my experience, most non-Catholic Christians intuitively grasp the idea that becoming saved involves a lifestyle change. Bible studies, youth groups, and other bonds of fellowship are very common.