I need to search for refundable air fares because I am not certain whether I will go on a trip or not, and the price of nonrefundable air fare has recently gone up (availability in my desired class just gone) so that it will be too much risk of no-showing the ticket.

Specifically, what I am searching for is either, in terms of preference (including nearby airports),
1. XMN - PRG - XMN
2. HKG - PRG - HKG
3. HKG - PRG - XMN

The departure date is 3 - 5 Oct, with daytime flights highly preferred, and return date is 8 or 9 Oct.

By searching on Expedia or Orbitz with the refundable fare option, it seems that it is returning fully refundable fare only (by comparing with its Aeroflot price) - I need to search for partial refundable fare as well such I can decide the risk ratio using the cancellation cost. For example, the cancellation cost of a CL Aeroflot ticket is US$40 which is reasonable if there is like ~70% chance of making the trip when compared to a cheaper non-refundable ticket or a MUCH more expensive fully-refundable ticket.

Where can I search for partially refundable air fare?