Karnatakabhashabhushana 8.24.2

8.24.2

paunaḥpunyaṁ bhr̥śārthō vā kriyāsamabhihāraḥ. tasminn arthē vivakṣitē madhyamapuruṣaikavacanasya it, ut, ēt ity ētē ādēśā bhavanti. prāyō lōpaś ca.

Repetition or intensity of an action constitutes 'intensity/repetition of action' (kriyāsamabhihāra). When that meaning is intended to be expressed, 'it', 'ut', and 'ēt' become substitutes for the singular of the intermediate person (second person); and generally, elision [occurs].