I have started running for witness last month, however I am very low on the rank because many witnesses, that are not active, are ahead of me.

Some of them have dozens, hundreds, even thousands of blocks missed, because they have received lots of votes in the past. Which means the blockchain trusts them to produce a block, but because their server is offline, they do not produce any block that gets assigned to them.

My witness node is prepaid for 1 year, so I know that for the next 1 year, regardless of my financial condition, it will keep producing any block that gets assigned to it, however it may take a lot of time until I get enough votes, since the runner witness (one per minute) is chosen based on the ranking and how many votes they get, even if they are "dead".

I hope to get more votes to even at a lower rank be assigned and produce the blocks properly.

It is everybody's duty to check their witness list and remove the vote from the ghost ones, because they make the blockchain spend time on blocks that do not get produced within the time allocated to them.