How to send data from an Arduino GPRS module to a Django application hosted on Heroku?
There's a number of errors in your program regarding your understanding of basic networking:

Let's start with this bit:

String scnt = "AT+CIPSTART=\"TipCP\",\"" ;
scnt += s_ip ;
scnt += "\",80\r\n" ;


That constructs a string:

AT+CIPSTART="TipCP","https://&lt;appname&gt;.herokuapp.com",80


and sends it to the modem.  Now:


There is no such protocol as "TipCP" - I think you meant "TCP"
You need to provide an FQDN (Fully Qualified Domain Name), not a URL.  FQDNs don't start with "https://".  I think you meant to use "foobar.herokuapp.com" where "foobar" is the name of your application.


You then go on to form a GET request and send it.

Now: the URL you used instead of an FQDN starts with https:// - that tells me you want to be using SSL for your communications. I don't know if that is required for Heroku or not, but if it is then you cannot use AT+CIPSTART with it unless you feel like trying to implement the entirety of SSL in your program. Also you would be connecting to port 443 not port 80.

Assuming you don't need SSL fixing your protocol and FQDN may be enough. However using the AT+HTTP... commands instead of manual manipulation of a raw TCP socket may be an easier option.

If you do need SSL (and it is advisable that you do if you can) then you will have to use the SIM900's AT+HTTPS... command set (detailed here).