Hi,
sorry but for each field you have a column in table, MySQL have a hard limit for length of columns.
To increase the number of columns you must to decrease the length of each single column. for example the standard length of select/radio/checkbox field is 255, these fields have predefined values, so for example if you have radio with 2 values 1,2 you can set the length of column to 1 char.
Another way is to convert the table engine from MyIsam to InnoDB. InnoDB engine not have this limit but has lower performance, to do this you can find some guide on the network.