How can I change a URL that an application pings I'm trying to resurrect an old mac application.

Currently it is trying to scrape data from deadurl.com/?12345

Although that url is dead so it's not working. There are other url's which provide the same data and are still alive such as

differentWorkingUrl.com/?12345

Is there a way I can decompile the application and replace the scraping URL?
What you want to do is to is first find the IP address of the website which has the data you need. Enter this command in Terminal (only the dot-delimited portions, no slashes or anything): 

nslookup deadurl.com


You should get a non-authoritative answer. This is what you want. Copy that address, and then enter this command into Terminal:

sudo vim /etc/hosts


You'll have to enter your password and press return to proceed. Note, for security, it won't show as you type. Once you're in the host file, move the cursor down to the bottom by pushing the function key, and the down arrow. Then press the "o" key, and paste the IP address, press tab, and type workingurl.com, replacing workingurl.com with your working URL.

Now press escape, ":", "x", return.

Now, assuming the software doesn't circumvent the hosts file in some way, it should have its communications redirected to the working URL, assuming the URL's path hasn't changed beyond the domain name.