Rashi: It drips. I.e. it constantly decreases.

Radak #1: It melted, from great sadness, like "va'Yimas Levav ha'Am."

Radak #2: [It drips] tears, like "b'Mistarim Tivkeh Nafshi" (Yirmeyah 13:17).

Malbim: The Pikudim arouse the miraculous way. My Nefesh drips from sadness, why do You not do with me miracles, like the Pekudim show [that You did in the past]?

Radak: Sustain me in my kingship, like Your words that You told me via Nasan ha'Navi "Kis'acha Yihyeh Nachon" (Shmuel II, 7:16).

Malbim: Sustain me like Your Pekudim show, that You give, to those who fear You, miracles to show their elevation.