var healthplayer = 150;
...
PANEL* first_pan =
{
	pos_x = 1077;	//It works, but only for one screen resolution!
	pos_y = 919;	//The same here!
			//Fix: Function which updates the position
	bmap = "healthbarframe_bmp";	//Forgot quotation marks
	window (1080, 919, 65, 25, "healthbar.bmp", healthplayer, 0);
	//Can be used directly without new panel
	digits (1100, 900, 3, "Arial#15b", 0.667, healthplayer); 
	//Same here
	flags = SHOW;
	//Refresh isn't needed anymore
	layer = 1;
}

//Your snippet:
if (healthplayer < 150)
	healthplayer = minv(150,healthplayer + 0.03 * time_step);	//Timestep needed because of different frame rates!