Hi.
There is no AJAX call but there are a few functions you can use:
mycred_add
You can use this function to add points to a user along with a new entry into your log.
mycred_get_settings
This function gives you access to the myCRED_Settings class and gives you further options. For example you can use it to update a users balance without a log entry:
// Load myCRED
$mycred = mycred_get_settings();
// Update balance (add 10 points to the given users current balance
$mycred->update_users_balance( $user_id, 10 );
Remember that users balances are stored as a user meta and you can always update a users balance by updating this meta.
By default, myCRED stores each users balance under the mycred_default meta key. So you can always get or update a user balance directly without using any mycred functions.
Example:
$user_id = 1;
// Get users balance
$users_balance = get_user_meta( $user_id, 'mycred_default', true );
// Add 10 points
$new_balance = $users_balance + 10;
// Save
update_user_meta( $user_id, 'mycred_default', $new_balance );
Remember that if you use any myCRED function, make sure you wrap these functions in a function exists check to make sure your site does not crash when you update or disable the myCRED plugin.
Example:
if ( function_exists( 'mycred_add' ) ) :
mycred_add();
endif;