Check if a string variable is empty in batch script

@echo off
:loop
cls & Color 0A
echo Type what you want !
set /p "cide="
IF [%cide%]==[] (
     Cls & Color 0C
     echo You must enter something
     choice /d y /t 2 > nul
     goto loop              
) ELSE (
     Goto Next
 )

:Next
Cls
echo %cide% is entered
pause

You can try something like that :

@echo off
:loop
cls & Color 0A
echo Type what you want !
set /p "cide="
IF "%cide%"=="" ( 
    Cls & Color 0C
    echo You must enter something
    Timeout /T 2 /NoBreak>nul
    goto loop
) ELSE (
    Goto Next
)

:Next
Cls
echo %cide% is entered
pause