Circuit with reversing polarity and two microswitches

The circuit that you are using with only the buttons is perfect. My recomendation is the next:

If the simplest works, use it and don't make your life complicated.

You will need a memory element such as a relay to hold the current direction of the motor.

^{simulate this circuit – Schematic created using CircuitLab}

Here a DPDT relay and two microswitches are used. The motor M1 drives to the "left" when the top terminal is positive and to the right when the top terminal is negative.

Suppose the relay is dropped out. The top terminal is positive, SW2 and SW3 are in the positions shown. When the motor reaches the left limit, SW2 is actuated, energizing the relay. The motor immediately reverses, but the top contact has pulled in, keeping the relay energized through D2. The motor operates until SW3 is actuated, which interrupts current to the relay (D3 catches the flyback voltage). The relay drops out, releasing the hold contact and it remains dropped out, and we're back where we started.

Interrupt V1 to switch everything off (and it will always drive to the left when power is applied). Interrupt only the current to M1 and the memory of the previous direction will be maintained as long as V1 is applied (which means continuous draw if the relay is energized).

A solid-state solution could use a single CMOS gate package (eg. 1/2 a CD4011B) and a MOSFET H-bridge to drive the motor:

^{simulate this circuit}