Additional Information
If you are willing to go for 3rd method of extracting front panel strings to a text file and updating values, and in case you want to do it programmatically then it can be done using invoke node for the application, in
VI string category and method name
import.
Below is the picture shown for this invoke node:
Note this change of front panel elements can not be on run time and has to be done in development. You can't call this invoke node in same VI. For this you have to create a new VI which takes reference of target VI, and uses this property node to take a modified string text file with new values of front panel elements.