I don't think there is a way to access ERRORLEVEL from a Perl script to check what the ERRORLEVEL is *before* starting the Perl script. You can access it after calling a command with 'system', such as:

# successful command and exit code
system ('dir');
print qq(ERR Code = $?\n);
# UN-successful command and exit code
system ('dri');
print qq(ERR Code = $?\n);
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Note, ERRORLEVEL is a "special" Windows environment variable:

C:> set /?
[...]
If Command Extensions are enabled, then there are several dynamic envi
+ronment variables that can be expanded but which don't show up in the
+ list of variables displayed by SET.  These variable values are compu
+ted dynamically each time the value of the variable is expanded. If t
+he user explicitly defines a variable with one of these names, then
that definition will override the dynamic one described below:

%CD% - expands to the current directory string.

%DATE% - expands to current date using same format as DATE command.

%TIME% - expands to current time using same format as TIME command.

%RANDOM% - expands to a random decimal number between 0 and 32767.

%ERRORLEVEL% - expands to the current ERRORLEVEL value

%CMDEXTVERSION% - expands to the current Command Processor Extensions 
+version number.

%CMDCMDLINE% - expands to the original command line that invoked the C
+ommand Processor.
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You can try to get around this. Are you using pl2bat to get your Perl scripts to run on Windows? Just edit the resulting batch script to include a conditional:

if %ERRORLEVEL% 2 perl -x -S %0 %*
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Where '2' above is the desired ERRORLEVEL, or use 'if NOT %ERRORLEVLE% ...' to get the opposite effect.

What launches your Perl script? Is it a batch file? What is the command that's running before it? Perhaps there is a way to include the conditional check for the ERRORLEVEL in that "thing" that launches your Perl script.