Bash store variable between multiples runs [duplicate]

I would like to increment a variable if an execution failed.

I tested the logic by using a script like:

#!/bin/bash

if [ ! -f "/tmp/init" ]
then
    var=0
    echo $var
    export var
    touch /tmp/init
fi
if [ "$1" -eq 1 ]
then
    (( var++ ))
    export var
fi
echo $var

I obtain the result:

:~# ./script.sh 1                     
0
1
:~# ./script.sh 1
2
:~# ./script.sh 1
2

Is there an easy way to do this stuff?