There is no need to create a new profile for this employee if all their information already exists in the system.
You would just find their Employee Profile > Edit (pencil icon) > Employee Status > Mark them back as 'Current Employee'
Remember to note their leave date before you update the employee status.
In order to keep a record of their previously held position, you should mark their former job with the end date that you noted as their leaving date when you switched them back to a current employee and create a new job record to cover their new employment. You would do this under the Employee's Profile > More > Jobs:
One last thing to consider is whether you wish their two periods of employment to count as continued service. If you do, then you should leave the employee's join date as it was on the profile. In this way, any holiday allowance based on length of service will be unaffected.
However, if they are to be considered two distinct and discrete periods of employment, then the join date can be amended to reflect the join date for the new period of employment. In this way, the employee will need to start again with regard to the accrual of holiday based on length of service. Should you choose this latter option, you may want to consider purging the employee's past holiday data so they start with a completely clean slate