Why are remittance inflows slowing down in the Philippines?

They are anything but slowing down. Seasonal or temporary adjustments (or falls), are not impacting the growth patterns.

The projected growth for 2015 over 2014 is anticipated to be over 5%.

Higher remittances from overseas Filipinos together with increases in exports of goods and services will underpin current account surpluses this year and next. However, the current account forecasts are trimmed since April as imports are projected to rise significantly when reconstruction speeds up.

Source: Philippines: Economy