I know your going to say buy 2 more
No it is only wimps that use more than one arduino per project.
I can't see you have run out of pins with that lot, remember you can use that analogue input pins as regular digital input / output if you want.
If you have run out of pins then a simple port expander like the PCF8575 or the MCP23S17 will give you another 16 I/O pins. You can add up to eight of these chips to one arduino to give 16 X 8 X 2 = 256 input / output pins if you want.
If that is not enough for you then shift registers provide input or output pins depending on the type of shift register, to an almost unlimited extent.