can anyone advise me of a circuit to achieve up / down push button lap counting to drive a multi LED display, need to count from 00 to 99 in both directions.
Simple - no debounce so you could see numbers skipping. I don't recommend this, but it will help you to understand how the other circuits work.
Ideal - with debounce, works well. May want to change R4-R6 to 100kΩ and C17-C19 with 0.1uF to further increase debouncing capability for switches with a lot of bounce.
Extravagant - pushing up/down button once and releasing increases/decreases count by one; holding either button down will perform auto-repeat - digits will continue to advance for as long as you hold the button down. Also will flash the display and work with a remote module.
Although now I'd use a ULN2004 in place of the UDN2981 and flip the direction of the LED's (cheaper).