An initial Texas License to Carry a Handgun is valid for 4 years. Renewal licenses are good for 5 years.
Before the license expires, a renewal notification letter should arrive in the mail. It will state when your LTC expires and how to renew it.
DPS charges $40 for the renewal, however there is no classes or qualifications that have to be completed.
Go HERE to begin the Texas DPS license to carry / concealed handgun license renewal process.