For my block explorer ( http://explorebiblepay.com/ ) I saw that the indexing process occasionally wasn't exiting cleanly, leaving the index.pid file alone and then halting updates to the explorer later. I ended up writing a small bash script that reads the index.pid and looks for the process - if it isn't there, it removes the file. Scheduled to run every few minutes, this ensures that as long as the wallet is running, the explorer is never more than a few minutes behind.

That being said, when I look at Lich's explorer, a reindex may or may not be the explanation. I agree that the lower block number displayed indicates a partial index, but with a total supply of 0 and a price of 0, it could be something else is down. The hash rate is there, so the wallet is probably running, but depending on how he configured the total supply column, a reindex MIGHT be the explanation for the 0 there. As for the price of 0, I don't know if he ever had the C-CEX API configured to return a price...