Yes, attendees may be asked to pay to attend the kickoff function. If the cost of admission is to offset the cost of putting on the event, the candidate may attend the event. If, however, the admission fee amounts to a contribution to the campaign, the candidate may not attend the event.
(Opinion 95-24) (Opinion 00-10)

If the committee determines that attendees will be asked to make a contribution to the campaign fund, are there any restrictions placed on the attendance of the candidate at the function?

Yes, the candidate may attend a campaign fundraiser if the admission fee is not at the level that it amounts to a contribution to the campaign. Attendees may be asked to make a contribution to the judicial candidate's campaign. However, the solicitation for contributions should not be made by the candidate personally and should not be made in the candidate's presence because Canon 7(B)(2) prohibits a candidate from personally soliciting a contribution.