Need help on SQL query on grouping in SQL server

Question

I have input data like this

ABC	Lvl	Ref
2SZ46AV	0	2SZ46AV
2SZ46AV	1	934253-142
2SZ46AV	1	722979-002
2SZ46AV	2	708984-001
2SZ46AV	1	L16720-001
2SZ46AV	1	L37344-001
2SZ46AV	2	933274-001
2SZ46AV	2	L47720-001

I need a last column called ref output as shown in table which has the previous or last value of ref for each lvl  group

ABC	Lvl	Ref	Ref OutPut
2SZ46AV	0	2SZ46AV	NULL
2SZ46AV	1	934253-142	2SZ46AV
2SZ46AV	1	722979-002	2SZ46AV
2SZ46AV	2	708984-001	722979-002
2SZ46AV	1	L16720-001	2SZ46AV
2SZ46AV	1	L37344-001	2SZ46AV
2SZ46AV	2	933274-001	L37344-001
2SZ46AV	2	L47720-001	L37344-001