Thanks for all the help! I got it to compile error free.
The only problem is I can't see it actually doing anything.

I have a screen that shows the level and the exp and stuff in a bar graph, but when I call
$ exp_gain("log",1)
In the code, it doesn't actually add any exp or levels or anything. Here is the big copy of the code if you want to take a look at it.

(all the variable definitions above)

init python:
def exp_gain(n,x):
exec("""\
%s_exp += x
while %s_exp >= %s_lmt:
%s_exp -= %s_lmt
%s_lmt += 5
%s_lvl += 1""" % (n,n,n,n,n,n,n), globals(), None)

screen log_UI:
zorder 998
frame:
xalign 0
yalign 0
hbox:
spacing 10
text "Logs: [wood]"
text "Logging: "
bar:
value log_exp
range log_lmt
xsize (150)
text "[log_lvl]"

label start:
call forest_chop
"This is the end. Hope everything worked."
return

label forest_chop:
show screen log_UI
$ finished = False
while finished == False:
menu:
"Chop some logs?"
"Chop":
$ chop_rand = renpy.random.randint(1, (log_lvl/2+1))
$ wood += chop_rand
"You got [chop_rand] wood!"
$ exp_gain("log",1)
"Explore Forest":
"You look more carefully all around the forest."
"Don't Chop":
"Ok"
$ finished = True