repupgrade: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/sbin/repupgrade - from package: tog-pegasus

You may install the required package with command yum install {package}

Error in other languages:
repupgrade: bevel nie gevind nie
repupgrade: comandă negăsită
repupgrade: comando não encontrado
repupgrade: commande introuvable
repupgrade: command not found
repupgrade: käsku ei ole
repupgrade: không tìm thấy lệnh
repupgrade: komanda nerasta
repupgrade: Kommando nicht gefunden.
repupgrade: kommandot finns inte
repupgrade: komut yok
repupgrade: nie znaleziono polecenia
repupgrade: níor aimsíodh an t-ordú
repupgrade: no se encontró la orden
repupgrade: no s'ha trobat l'ordre
repupgrade: opdracht niet gevonden
repupgrade: parancs nem található
repupgrade: perintah tidak ditemukan
repupgrade: príkaz nenájdený
repupgrade: příkaz nenalezen
repupgrade: команда не найдена
repupgrade: командата не е открита
repupgrade: 命令找不到
repupgrade: コマンドが見つかりません