It depends on your circuit.

You need to make sure nothing puts voltages on programming pins (PB0, PB1, PB2, RST) white the programming is in effect.

If you design your circuit such that those pins are connected to LEDs or normally open pushbuttons, you will be able to reprogram it just fine.  If you connect other devices to those pins, you'll need to disconnect them somehow.

For example, in one of my devices I had a piezo speaker between PB0 and PB1. In order to program in the circuit, I had to put a jumper in series with the speaker, and remove it while programming.

It depends on your circuit.

You need to make sure nothing puts voltages on programming pins (PB0, PB1, PB2, RST) while the programming is in effect.

If you design your circuit such that those pins are connected to LEDs or normally open pushbuttons, you will be able to reprogram it just fine.   If you connect other devices to those pins, you'll need to disconnect them somehow.  

For example, in one of my devices I had a piezo speaker between PB0 and PB1. In order to program in the circuit, I had to put a jumper in series with the speaker, and remove it while programming.