Those fund returns look great for the period mentioned.
However, as you have mentioned, past results mean very little and on average actively managed mutual funds have lower returns than the indexes.
If you believe that some mutual funds return more than the average because of probabilities (luck) instead of better management (as I do) then you'd move all your funds to indexes. If you believe that the management does make a difference, then keep the funds (in this case, probably you should keep all of them as they have great returns).
However, as you have mentioned, past results mean very little and on average actively managed mutual funds have lower returns than the indexes.
If you believe that some mutual funds return more than the average because of probabilities (luck) instead of better management (as I do) then you'd move all your funds to indexes. If you believe that the management does make a difference, then keep the funds (in this case, probably you should keep all of them as they have great returns).