Update: Ohio is now permitless (constitutional) carryAs of June 2022 (Senate Bill 215), any qualifying adult 21 or older who can legally possess a firearm may carry a concealed handgun in Ohio without a permit. The Ohio Concealed Handgun License (CHL) described below is now optional — it remains useful for carrying in other states (reciprocity), the federal Gun-Free School Zones Act exemption, and as a background-check alternative when buying a firearm.

Licenses expire five years after the date of issuance or renewal. If you wish to renew your license, you may do so 90 days BEFORE the license expires. You should renew your license as early as possible.
Applicants residing in another state must renew with the sheriff that issued their previous license. If you no longer live or are employed in Ohio, you may not renew your license after it expires.
In order to renew your license, you must submit proof of competency certification.  If it has been over 6 years since your original certificate of training, you must take another class to get a new certificate.

Proof of certification may take either of the following forms:

  1. A previously issued Ohio concealed carry license. The license may be either expired or currently valid.
  2. A competency certificate from your instructor. If you have not previously renewed your license, you must show proof that at one time, you had a competency certificate.

Don’t bring your pistol with you when you submit your renewal at the Sheriff’s office!

Source & further reading: this overview is kept current against the CCW Hub Ohio Concealed Carry Guide — a regularly updated, statute-cited reference. Always verify current law before you carry.