Like all IEP meetings, things are very school dependent. Similar to your original evaluation period, they need to determine what tests to be done. This is done at a meeting and you do have input. Some schools might decide that no new testing is needed, while others might determine that a brand new set of academic, OT, ST, and psych testing is needed. The school has 60 days to perform the tests and to schedule another meeting to discuss the results and determine if your child is still eligible for the IEP. If the answer is yes, then another meeting is scheduled within 30 days to write the new IEP.
In general, it is easier to keep an IEP compared to initially qualifying for one. Do you have reason to believe that the team is trying to take the services or IEP away? If not, it is more of a formality to ensure that the child still has the disability and the IEP often stays the same or changes to meet the child's needs.