I'm pretty sure that SMB/CIFS shares are always lost when the computer goes into sleep mode. I'm not sure of any way to automatically remount the drive upon bringing the system back up, but you can always leave an AppleScript in the dock or on the desktop to remount the share without having to go through the finder dialogs. Here's the one I use:
Code:
tell application "Finder"
mount volume "smb://username:password@192.168.1.10/SERVER_ROOT/"
end tell
Save that as an executable AppleScript, drop it into your Applications folder, and drag a copy to the Dock. (Note: the line that begins "mount volume..." includes the quoted material in the same line, so this script should only be three lines, even though it may show up differently on the forums.)
While on the topic of Samba shares, does anyone else have trouble with random speed dropouts? Like files copying at about 10kB/sec? I switched over to NFS mounts and gave up on SMB except when there's no other option due to these random dropouts. I've had them since I started using OS X at 10.3.7, and update after update goes by in Tiger, and I never see it get fixed.