Vim move cursor one character in insert mode without arrow keys
Map ) to skip over the exisiting )
if it is a closing parenthesis
inoremap <expr> ) strpart(getline('.'), col('.')-1, 1) == ")" ? "\<Right>" : ")"
Taken from: http://vim.wikia.com/wiki/Automatically_append_closing_characters
Old Answer
:h i_CTRL-O
execute one command, return to Insert mode.
Ctrl-ol will move you one character to the right then return you to insert mode.
Alternatively some of the bracket plugins allow you to just type the closing bracket ) and they will override the existing one.