How can I reset the search filter when changing languages?

Try this.

function gd_snippet_20190903_wpml_language_page_url( $page_url, $page_id, $lang_code ) {
	global $sitepress, $geodirectory;

	if ( $sitepress->get_default_language() != $lang_code && absint( geodir_location_page_id() ) == $page_id ) {
		if ( ! empty( $geodirectory->location->country_slug ) && ! empty( $geodirectory->location->region_slug ) ) {
			$_page_url = explode( "/" . $geodirectory->location->country_slug . "/", $page_url, 2 );

			if ( count( $_page_url ) == 2 ) {
				$page_url = $_page_url[0] . '/' . $geodirectory->location->country_slug . '/';
			}
		}
	}

	return $page_url;
}
add_filter( 'geodir_wpml_language_page_url', 'gd_snippet_20190903_wpml_language_page_url', 20, 3 );

Kiran