Changing the number of cycles of an sinusoidal input signal
So yes, increasing the duration of the transmitted sinusoidal pulse (by increasing the number of cycles transmitted) will provide improved detection at the same SNR.

This is equivalent to a brute force bit duplication used to decrease the bit error rate (hence improve the reliable communication) at a given SNR. Note, however, that you will be transmitting at a slower rate than a shorter window. 

So in effect, this method of longer window will compromise transmission rate vs improved detection at longer distance (lower SNR).