can I extend a multi-entry L visa in China? what if they reject it?

Currently I hold a multi-entry L visa with 30days of each stay. I heard that we can extend an L visa maximum twice, but can I extend it in China local PSB without go out of China to get a new entry? what if they reject it? should I go back to my country or is there a better option? and what is the fee for L visa extension for an Indonesian passport holder?

can I apply another L visa in China when my first L visa expired?

can I get a year residence permit with an L visa?
thank you.