When you say "change the spare" I am presuming you mean add it into the RAIDset for additional space?
Please let me know what RAID level you are currently using and what firmware and model the EQL array is.
Running without spares is allows on selected RAID levels.
Generally speaking it is not a good idea to run RAID without spares. I would strongly suggest you have several cold spares available. One problem with cold spares is they are not periodically tested.
Sorry, if the RAID policy has been set to "no spares" there is no way to revert back to a spares consideration without first resetting the array. There is no way to maintain the data and configuration. Once the spares are added there's no reversing it.
If you had an array that was large enough to hold the data that you could add to that group then you could evacuate the member out of the group the add it back in using the spares based RAID policy.