Changing the number of iterations in a for loop

I have code like this:

loopcount = 3
for i in range(1, loopcount)
   somestring = '7'
   newcount = int(somestring)
   loopcount = newcount

so what I want is to modify the range of the for 'inside' the loop.

I wrote this code expecting the range of the for loop would change to (1,7) during the first loop, but it didn't happen.

Instead, no matter what number I put in, it only runs 2 times. (I want 6 times.. in this case)

I checked the value using print like this:

    loopcount = 3
    for i in range(1, loopcount)
       print loopcount
       somestring = '7'
       newcount = int(somestring)
       loopcount = newcount
       print loopcount
#output:
3
7
7
7

What is wrong? the number has been changed.

Where is my thinking wrong?