AS @ABG has already said, you use the HW Serial line of Arduino to send/receive text on both the Serial Monitor and the BT line. This is not allowed (everything you send/receive from/to the serial monitor will also go to the HC05, therefore creating a mess toward the app).
If you want to still let usable the serial monitor line, you shall rather use the SoftwareSerial library (supposing you are using a UNO board) to connect the HC05 to two different pins of the UNO. The library can be downloaded from the GIT repository on the web. If you use the 2.x.y series of Arduino IDE you can load directly from the library menu (the latest version is called NeoSWSerial):
For the HW connection between CPU board and HC05 please refer to the drawing annexed to my first post: though it is related to a Nano CPU board, the same can be applied to boards having the AVR microprocessor (i.e. Nano, Uno, Micro, Mega,...)
Then apply all @ABG has written. Pay attention to the terminator character: this means that when you transmit from Arduino to the App, ONLY the last sending shall be made by using a .println(); Previous transmissions shall be made by using only .print();
For example: supposing that you have named your BT serial line "BTserial" when you send some data to the app you shall write
BTserial.print("data1"); // first data
BTserial.print("data2"); //second data
BTserial.println("data3"); //last data
Anyway, these are just chunks of code. It would be much better if you follow step-by-step the FAQ from @ABG
EDIT:
try also to have a look here:
You'll find both the .aia and the .ino working codes (for a Mega Arduino board).