In your experiment, since you start seeing a decrease in signal intensity when using the same antibody 3rd time, my suggestion would be to not go beyond 2nd time. Never reuse secondary and always make it fresh the day you are using.

Yes, you can reuse primary antibodies several times, the reason why you are losing the signal as mentioned by Rasmi is that every time antibodies get attached to the sample depending on affinity and the amount of the target protein as well initial concentration, every time you lose the concentration of antibodies and eventually, you don't have enough antibodies to produce the signal. I have reused antibodies up to 3-4 times. Secondary antibodies do form complexes with primary sometimes rendering neutralizing primary sometimes not. To keep things simple it is better to not reuse secondary ab they are inexpensive and usually available. Regardless of reusing antibodies or not always add the negative control sample (without primary incubation but with secondary) to evaluate your secondary non-specific binding and levels of sample autofluorescence.

It is possible unless your antibody is not affected by the ICC process. However, if you are performing a time-dependent experiment( example: effect of drug treatment), try to avoid reusing it as it will not reflect the real protein expression level on your cells.

Good luck!