Trademarks: Replying to a Trademark Examiner

I have applied for a US trademark and received a reply from the examiner stating, essentially,
that the specimen doesn't show the mark associated with the services claimed in applicant’s identification, the specimen shows a website allowing users to upload media for entertainment purposes, but the applicant’s identification outlines a website allowing that function but for business purposes.

So, does this mean I need to reply with a new classification?

Also, if I reply with a different classification and the examiner doesn't think it's correct again, what happens next?

Is there a cost every time I submit a response?

Thanks, I look forward to being enlightened

Trademarks: Replying to a Trademark Examiner