how can i increase the limit of 250

how can i increase the limit of 250 items that i can put on sale?
I would like to sell more than 250 at a time

Are you referring to Bot limit? If so, the only way is to sell them. The more you sell, the more limits you have. They don’t want people to put junk in their bots (ex: items worth a few cents but advertised at 10-20x values).