.net Desktop EXE application update

hello we have a .net VPN application which do the following: 1. import the list of servers from json list hosted on the server 2. support conneting to protocols PPTP, L2TP, SSTP, openVPN TCP and UDP. 3. Connecting to a dedicated Server by adding the Hostname, USername and password after choosing the needed Protocol. we have the source code of this application and all what we need is to change the OPenVpn certifiate and add another tap for the application which will use new json list as its for new product. Also we want to update it and make sure that its working now with windows 10. i belive its working good but to make sure. its simple change and