How to increase Current in DC Adapter
Short answer: You can't and shouldn't try.  Get the right power supply.

Small and cheap power supplies are built in high volume and optimized for the lowest cost to just meet the specs.  In some cases with less reputable manufacturers, they don't even meet their own specs.  If your power supply contains the component to support 1 A of output current, they would have sold it as a 1 A supply because they could have charged more money for that.  By the time you "modify" this supply to support 1 A, you will have essentially built your own supply.

Judging from the level of electronics understanding exhibited by your question, you also shouldn't be messing with anything connected directly to the power line.  You could make the whole supply unsafe so that you kill yourself some time later.  Worse, you could set your neighborhood on fire.